CT Why didn't Vader sense Leia as his spawn?

When Vader is torturing Leia in ANH, I presume it's only them and the droid. Pain and the pleasure of watching someone in pain can be very powerful emotional triggers, which I believed was a tool through which the Force evoked its influence, so how come Vader didn't get the realization that Leia was his until the third film? Surely there had to be some Force connection in such an intimate experience and environment?

 

I don't think there any in-universe explanation other than the fact that he thought he had no kids. So any possible connection he might have felt, he dismissed it. It was upon learning Luke's last name that he considered that he had a son.

 

Out of universe, she wasn't his child at the time. In universe, good question. I think Lucas said something about her mastering the equivalent of Bene Gesserit self-control (he took a lot from Dune), though I'm not entirely sure where - it may be in one of the earlier script drafts.

 

I think the key is that she didn't know. Where would Vader have pulled such information from: her DNA? I mean, first, "her resistance to the mind probe is considerable" and all that. So if it's a mental procedure, the question is what she has in her mind. And she has no idea that Anakin Skywalker was/is her father.

 

Vader only knew about Luke when he demonstrated a considerable connection to the Force by talking with Obi-Wan during the DS trench run: "The Force is strong with this one." (ANH)

Apparently, Jedi and Sith have distinct Force signatures that can only be read when the person in question is using his/her Force abilities. For instance, the Emperor did not know about Luke until he started to become stronger on Dagobah. In fact, he even knew the new enemy was the Son of Skywalker just by sensing him through the Force.

Since no one trained Leia, her Force signal likely wasn't strong enough to be sensed

 

spawn. lol.

 

I think this is how they first become aware of a person possessing a strong connection to the Force. But once they have become aware of that person or been in his or her company for a long while, they can detect that Force user's presence without the latter having to do anything. Look at how Obi-Wan and Anakin were aware of each other's presence in "A New Hope" or how Anakin and Luke were aware in "Return of the Jedi".

 

Jedi and Sith can sense certain individuals that they form a connection with through the Force. These "tremors" are recognizable due to time spent together which is why Vader realizes that Obi-wan is indeed alive and aboard the Death Star.

VADER: "He is here..."

TARKIN: "Obi-Wan Kenobi! What makes you think so?"

VADER: "A tremor in the Force. The last time I felt it was in the presence of my old Master."

Though sometimes it can be difficult to detect over a distance as shown in "The Siege Of Lothal" when Ahsoka tried to identify who the TIE pilot was that was making mincemeat out of Phoenix Squadron and got an unexpected surprise.



But a common thread seems to be that only after the Force is felt in sufficient usage can the distinct "tremor" be felt and then recognized all the time. Vader senses Luke when he goes to destroy the Death Star, but once this connection is established on his end, he can feel Luke and identify that particular "tremor" as his own. Once Luke is familiar, he can do likewise as ROTJ demonstrated. Only when one is trying to mask themselves in the Force, can their presence not be detected. Something that was common in the old EU.

 

The dark side probably clouded his mind.

 

Anakin didn't know Padme was pregnant with twins, let alone a son and daughter. Leia didn't know her who her birth parents were, especially her father. There was no way for them to know.

Now was Leia trained by Bail somehow to resist Imperial mind probes? That is interesting.

 

The short book Captive of Evil (Princess Leia's diary of the events of ANH) mentions that she's been training herself to resist pain, by holding ice cubes and that sort of thing.

It also shows us the whole scene from her point of view. Pretty grim, for a book aimed at younger readers:

Star Wars Journal: Captive to Evil
I'm weak. And dizzy. It's hard to speak or even lift my head. I can't make it to my cot. I'm lying on the floor.
Like an animal. This is what they did to me.
I try not to feel hatred. Because that's what they want. Hatred weakens the spirit as pain weakens the body.
I didn't think such pain existed. In any universe.
I have to rest now. To prepare for next time. But I record this fact.
He ... did not ... break me.

The torture began with one needle. It probed my most sensitive nerves. Darth Vader stood by. The pain grew until I broke my promise not to scream and let out a cry that came from the deepest part of myself.
I practiced my mind techniques in the beginning. But as the pain began to take over, I could no longer reason properly. And then, as my sanity was slipping away, Vader spoke to me. He spoke in the voice of a friend. He wanted to end my pain — didn't I want it to end too? It would be so easy. It would happen immediately. All he had to do was raise his hand. And all I had to do was reveal where the Death Star plans were, or the location of the hidden Rebel base. Either piece of information would bring me sweet relief.
I held on.
"Never," I gritted out. Just that one word cost me a great deal of effort.
The needle probed deeper. The pain grew and grew until I lost consciousness. They revived me.
And then they started all over again.
More pain. More terror.
I would have broken if I hadn't been trained so well. I clung to the pieces of my training that had been shattered by the pain. Vader used the Force, trying to convince me that he was working for the Rebellion. That my father wanted me to reveal the location of the hidden base. Didn't I want to please my father?
Confused and in raging pain, I held out against that voice. In the end, my resistance became nothing more tan a single point of consciousness. A pinprick of light illuminating the darkness around me. I concentrated and concentrated on that tiny particle of light, knowing that if I let go—all was lost.
Then from somewhere far away, I heard Vader's voice. I heard him say "Enough."
He wanted me alive. They would try again later.
My eyes were closed, and my grip on consciousness was weak. But I heard the hiss of the door with relief.
I'd made it through.

 

I happened to like what "Shadows Of The Empire" wrote with Leia getting angry which caused Xizor's pheromones to stop working. I think that if Leia had gotten angry and scared enough, that nothing could be done to break her that way.

 

Vader: "Hm. Princess Organa reminds me of P... naaawww."

 

I'd rank that the most logically, straightforward, in-world answer you can get without overcomplicating the premises.

 

I agree with everything said about Leia not having been tapped into her Force abilities. But also consider Vader's priorities at the time, being a high ranking Imperial officer and pilot, commanding a moon sized space station, Tarkin breathing down his neck at every move, he had to perform his duties, especially given the recent blunder by the Empire of allowing their Death Star plans to be stolen. It wasn't until later on that he detected Obi-Wan's presence, which raised his awareness, and only in a moment of intense focus during combat that he detected Luke after Luke had tapped into his own Force abilities.

 

It seems like a plot hole to me. In the EU, force-users sense other untrained force-users all the time. Palpatine and Plagueis use it like radar to search for enemies or disciples to train. Even in the films, it seems that Palpatine can sense things about non-Force-users. For instance, he knows that the Padme is Anakin's wife and that she seems destined to die. When he reveals this to Anakin, Anakin is surprised, indicating that he never shared this info with Palpatine before. Palpatine also senses that the Rebels using the Imperial shuttle are approaching Endor, though he strangely doesn't sense Luke.

Since Palpatine can sense these things about non-Force-users, it seems like Vader should be able to sense that Leia is his daughter and that she is strong in the Force. Also Leia senses Luke on the bottom of Cloud City, and she's had no training with the Force, so again, if an untrained Leia can sense this, then a highly-trained very powerful Sith lord should be able to sense these things about Leia. Luke also senses Leia's and Han's future, so why wouldn't Vader sense Leia's past and the fact that she's his daughter.

For me, it makes so little sense that I've created my own head canon. In my version, Vader does sense something about Leia in ANH, but he doesn't have time to investigate it. That's part of why he let's them escape. He wants to figure out what makes her special. Later, in TESB, Vader prevents Boba from shooting at her in the carbon freezing chamber because he suspects something about her, and that's also why he wants her to be taken to his Star Destroyer. In ROTJ, Vader does read Luke's mind and realizes he's thinking about Leia, but this doesn't surprise Vader because he's always suspected it, and that's also why he doesn't act surprised. However, Vader pretends as if he's just learning it then because he wants to anger Luke by making him feel like his thoughts betrayed his sister.

To me, this scenario makes more sense than Vader not sensing anything special about Leia even though he was in close proximity of her on a number occasions on the Death Star and Tantive IV.

 

He seemed more overtly surprised in the novelization:

He was picking up additional feelings from Luke, now, new crosscurrents of doubt. Remorse, regret, abandonment. Shades of pain. But somehow not directly related to Vader. To others, to ... Endor. Ah, that was it - the Sanctuary Moon where his friends would soon die. Luke would learn soon enough: friendship was different on the dark side. A different thing altogether.
"Give yourself to the dark side, Luke," he entreated. "It is the only way you can save your friends. Yes, your thoughts betray you, son. Your feelings for them are strong, especially for-"
Vader stopped. He sensed something.
Luke withdrew further into shadow. He tried to hide, but there was no way to hide what was in his mind - Leia was in pain. Her agony cried to him now, and his spirit cried with her. He tried to shut it out, to shut it up, but the cry was loud, and he couldn't stifle it, couldn't leave it alone, had to cradle it openly, to give it solace.
Vader's consciousness invaded that private place.
"No!" screamed Luke.
Vader was incredulous. "Sister? Sister!" he bellowed. "Your feelings have now betrayed her too ... Twins!" he roared triumphantly. "Obi-Wan was wise to hide her, but now his failure is complete." His smile was clear to Luke, through the mask, through the shadows, through all the realms of Darkness. "If you will not turn to the Dark Side, then perhaps she will."
This, then, was Luke's breaking point. For Leia was everyone's last, unflagging hope. If Vader turned his twisted, misguided cravings on her ...
"Never!" he screamed.

 

Not sure if it's been mentioned already, but Vader thought his children were dead. He wasn't going to assume/sense Leia was his child...that he thought died by his own hand 20 years ago. As Iron_lord posted, it wasn't until ROTJ when he learned that yes, Leia was in fact his daughter.

 

I am sure that this is old BUT ... I always liked the idea that Vader was super confused by Leia in ESB when she escaped from Hoth. He sensed *someone* a Falcon, who I like to think, he took to be Luke, which explains why he went hell bent on leather, chasing the Falcon whilst letting X-wing + real Luke escape.

I think that it was only after he arrived in Bespin that he worked out he was mistaken and then went for the bait business...

He had no connection with either of the twins in ANH because then of course, George hadn't worked out that they were related to Darth..

 

Vader didn't know that Luke was even Force sensitive until the latter used it during the Battle of Yavin. He didn't know that Luke was his son until a spy told him. So, I don't see how he could have known or "sensed" that Leia was Force sensitive or his child in "A New Hope". I find this complaint a bit illogical.

 

Practical answer: It hadn't been decided in ANH that Vader was Leia's father yet.

Other answer: The darkside clouded his mind. It made Vader arrogant and he was too caught up in his anger and hatred to notice what was infront of him. He truly believed Padme and the children had both been lost at the end of ROTS, why would he bother probing Leia for any relation? It wouldn't make sense. Plus, it's in Vader's nature to automatically block out anything that brushes against his past as Anakin Skywalker. He could've rejected the notion the minute it even slightly touched his subconscious...

 

The movie had never established that Force sensitive people can automatically sense that someone else is Force sensitive, unless: a) that second person has used the Force in his or her presence; or b) or the first person has past experiences with the second person.

Vader had never been in Luke presence before. Luke had ever used the Force in Vader's presence, until the former used it during the Battle of Yavin. Vader didn't find out that Luke was his son, until a spy told him who was one of the heroes of Yavin. Vader had met Leia before, but she had never used the Force in his presence. And the only time she may have used the Force is when Luke communicated with her near the end of "The Empire Strikes Back", when Vader was obviously not around. It's not surprising that he didn't know she was his daughter, until he sensed Luke's very obvious thoughts in "Return of the Jedi".

I have to stand by my belief that it would have been illogical for Vader to automatically sense that Leia was his daughter.

 

It seems to me very simple. The rule of thumb seems to be a Force user can sense the thoughts/feelings of others. Vader learned about Leia as his daughter by probing Luke's feelings. But since Leia didn't know Vader was her father at the time, he couldn't sense that information from her.

There are other sources that seem to back this up. In the council chamber, Yoda tells Anakin "See through you we can". They can easily sense his strong feelings over his mother. Obi-Wan also tells Luke "Bury your feelings deep down..." Obviously, Obi-Wan was much more practiced at this, and failed to allow Vader to get any information from him at their 2nd duel.(Although, I'm sure Vader was more revenge minded than anything).

I think there was originally something in the ROTJ script regarding the Emperor sensing Yoda's fate from reading Luke's feelings.
The Emperor: "There was one called Yoda. Lives he still?"
Luke doesn't answer
The Emperor: "Ah. He does not."

 

Don't know about scripts - but it was certainly in the novelization:


"Tell me, young Skywalker," the Emperor said when he saw Luke's first struggle had taken its course. "Who has been involved in your training until now?" The smile was thin, open mouthed, hollow.
Luke was silent. He would reveal nothing.
"Oh, I know it was Obi-Wan Kenobi at first," the wicked ruler continued, rubbing his fingers together as if trying to remember. Then pausing, his lips creased into a sneer. "Of course, we are familiar with the talent Obi-Wan Kenobi had, when it came to training Jedi." He nodded politely in Vader's direction, indicating Obi-Wan's previous star pupil. Vader stood without responding, without moving.
Luke tensed with fury at the Emperor's defamation of Ben - though, of course, to the Emperor it was praise. And he bridled even more, knowing the Emperor was so nearly right. He tried to bring his anger under control though, for it seemed to please the malevolent dictator greatly.
Palpatine noted the emotions on Luke's face and chuckled. "So, in your early training you have followed your father's path, it would seem. But alas - Obi-Wan is now dead, I believe; his elder student, here, saw to that -" again, he made a hand motion toward Vader. "So tell me, young Skywalker - who continued your training?"
That smile, again, like a knife. Luke held silent, struggling to regain his composure.
The Emperor tapped his fingers on the arm of the throne, recalling. "There was one called ... Yoda. An aged Master Jed ... Ah, I see by your countenance I have hit a chord, a resonant chord indeed. Yoda, then."
Luke flushed with anger at himself, now, to have revealed so much, unwillingly, unwittingly. Anger and self-doubt. He strove to calm himself - to see all, to show nothing; only to be.
"This Yoda," the Emperor mused. "Lives he still?"
Luke focused on the emptiness of space beyond the window behind the Emperor's chair. The deep void, where nothing was. Nothing. He filled his mind with this black nothing. Opaque, save for the occasional flickering of starlight that filtered through the ether.
"Ah," cried Emperor Palpatine. "He lives not. Very good, young Skywalker, you almost hid this from me. But you could not. And you can not. Your deepest flickerings are to me apparent. Your nakedest soul. That is my first lesson to you." He beamed.
Luke wilted - but a moment. In the very faltering, he found strength. Thus had Ben and Yoda both instructed him: when you are attacked, fall. Let your opponent's power buffet you as a strong wind topples the grass. In time, he will expend himself, and you will still be upright.
The Emperor watched Luke's face with cunning. "I'm sure Yoda taught you to use the Force with great skill."
The taunt had the desired effect - Luke's face flushed, his muscles flexed.
He saw the Emperor actually lick his lips at the sight of Luke's reaction. Lick his lips and laugh from the bottom of his throat, from the bottom of his soul.
Luke paused, for he saw something else, as well; something he hadn't seen before in the Emperor. Fear.
Luke saw fear in the Emperor - fear of Luke. Fear of Luke's power, fear that this power could be turned on him - on the Emperor - in the same way that Vader had turned it on Obi-Wan Kenobi. Luke saw this fear in the Emperor - and he knew, now, the odds had shifted slightly. He had glimpsed the Emperor's nakedest self.
With sudden absolute calm, Luke stood upright. He stared directly into the malign ruler's hood.
Palpatine said nothing for a few moments, returning the young Jedi's gaze, assessing his strengths and weaknesses. He sat back at last, pleased with this first confrontation. "I look forward to completing your training, young Skywalker. In time, you will call me Master."

 

Sensing someone presence through the Force doesn't mean knowing someone's heredity. Vader can't sense Leia was his daughter because neither of them knew they were related.