Lincoln: I got something for you, Liv.
Altlivia: Really? What’s this?
Lincoln: A pendant from my former partner, Robert. It’s Native American. The maze represents the journey of life. The obstacles, making the right choices. Until we find ourselves in the centre.
Altlivia: What’s in the centre?
Lincoln: Home. A place to belong. Where the heart is.Fringe AU: in which Lincoln kept Robert’s pendant all along - one day after the bridge closed, he decided to give it to Altlivia to confess his love for her…

You deserve all the happiness you got.(Alt)Olivia Dunham with Lincoln Lee then and now
- Fringe 4.18 & 5.12

ANYWHERE BUT HERE → an altliv/lincoln mix
when a heart breaks - ben rector ♫ between the raindrops - lifehouse ft. natasha bedingfield ♫ heartlines - florence + the machine ♫ counting stars - onerepublic ♫ to be alone with you - sufjan stevens ♫ your love is a song - switchfoot ♫ forever - matt hires ♫ anywhere but here - safetysuit
Here’s a question I have been pondering ever since I first watched Fringe episode 4.20 - at exactly which point did Lincoln realise he fell in love with Altlivia? What was the defining moment?
Lincoln and Altlivia first met briefly in 4.1 then he finally got to familiarise himself with Altlivia in 4.8 and 4.9 but under somewhat antagonistic and skeptical circumstances in the beginning. They warmed up to each other near the end of 4.9 given their collaboration and how matters cleared up and when they met again in 4.17 they obviously enjoyed each other’s company. Lincoln was relatively shy while Altlivia was cheery, radiating and accommodating and Altlivia seemed to find Lincoln’s demeanors intriguing and adorable (for the lack of a better term). They had chemistry working together as partners and got to communicate on a personal level. At the end of this episode the unthinkable happened and the tragic end brought these two closer. Lincoln offered his company and Altlivia accepted it. Was it then that he started to develop feelings for her? To me something was apparently brewing. 4.17 and 4.18 must have happened in a relatively short time span because 4.18 picked up from where 4.17 left off (Alt!Lincoln’s funeral) thus I assumed only several days to a few weeks at most have lapsed. By the end of 4.18 Lincoln told Altlivia that he decided to remain in the alternate universe until they could apprehend the culprit to AltLincoln and Robert’s murder. Was that the only reason for his stay during that time? Besides keeping Altlivia company while she was mourning the loss of Alt!Lincoln and be her partner to help solve the cases, did Lincoln also wanted to spend more time with her for his own personal reasons? Were there affection and love already? 4.19 was an episode that offered a glimpse into the future then 4.20 returned to the present and we witnessed how the cortexifan kids were used to trigger earthquakes that could potentially collapse both universes and therefore the bridge must be closed. That was when Lincoln decided to stay in the alternate universe permanently. Was Peter’s “home is where the heart is” a wake-up call/cue for Lincoln to confront his own feelings and anxiety? Was it then that he realised he really loved Altlivia and loved her to the point that she was worth giving up his own universe??? This had been somewhat baffling and puzzling to me because we had no idea what happened to them off-screen between 4.18 and 4.20 and how much time actually lapsed between these two episodes for Lincoln to be this determined. I assumed this chain of events happened in a short duration and he acted upon his gut feeling.
Fortunately for us, Fringe’s producers didn’t end the series with a cliffhanger on Lincoln and Altlivia’s relationship in 4.20. In 5.12 we learnt that Lincoln made the right and best decision - he lived happily ever after in the alternate universe with Altlivia, built a family of his own and finally found his sense of belonging. I just thought it would be lovely if the pairing had more screen time and we could learn more about their relationship.
I think all of us who ship Linham, or would like to ship Linham, wished they would have got more screentime. It is really frustrating when you love a pair so much and think of all the potential they have, but don’t get to see any of it.
Anyway, about your question, I think I made a post back in the day when 4.20 aired, talking about this issue. This is basically my POV on the thing:
I don’t think Lincoln was totally in love when he decided to stay in the redverse. He had feelings for Liv, sure, but at that point there was nothing concrete between them.
I do think they hit it off right from the start. Ok, maybe not in 4.01, because they just saw eachother, they didn’t talk. But in 4.08, when Liv and altLinc arrested Lincoln, she always was very nice to him, and believed in him despite of how crazy his theories sounded. And I think Lincoln, by knowing the other Olivia, and by what Peter had told him of Liv, already had a good predisposition towards her.
From that moment Lincoln felt comfortable around Liv. She was easy going, she was nice and fun. I think she was exactly what Lincoln needed in his life. And Liv had already said onscreen she liked the “good guys”. And if Lincoln is not the poster boy for “Good Guys”, IDK who is, honestly.
I think when Lincoln told Liv he wasn’t going anywhere until they found who had killed altLinc and Robert, he was being honest. But I also think he wanted to stay because he clearly felt better around Liv than with the amber! Team, and because he didn’t want to leave Liv alone. He saw her suffering for the lost of altLinc, and while at first he thought seeing him might not be good for her, he later understood that on the contrary, he was good for her too. We never saw Liv resenting Lincoln’s presence on her world, but totally the opposite. And while psychologically speaking, it probably affected her mourn of altLinc (sounds reasonable, and it was a opinion several people had back then, that it wasn’t good for Liv that Lincoln stayed there), what we got onscreen showed totally the opposite.
Now, we don’t know how many time passed between 4.18 and 4.20, so we don’t really know how much time they were working together before Lincoln made his final desicion. I don’t think there’s any hints to help us figure how many time passed. It could’ve been easily several weeks. Several weeks were they spend everyday together, and that I think helped Lincoln realize that he really felt there more at home that he ever felt in his adult life before, in his own world.
So when the issue of the bridge having to get closed happen, up until then I don’t think Lincoln had made any desicion, but like you mentioned, what Peter said, and the urgency of the situation made him take it. There was no other way. If he didn’t do it, he would lose every chance of discovering if there was really something more between him and Liv, and the chance of feeling again as good as he felt on the redverse. With this I mean that, while is clear that Liv was the major reason for Lincoln’s desicion, she wasn’t the only reason. It was everything. How he felt respected by the Fringe Division, how he felt he really could be of help there (while, like he said, he wasn’t as needed in the amberverse, because they already had a full team), and because for some reason he felt more comfortable in his own skin there.
So he took the chance. Even if Liv and him didn’t become a couple, he wanted to be there, he wanted to have her around (though I imagine that Lincoln could sense that Liv liked him too). I think that’s what he learned from his stay in the redverse and from alt Linc. That he needed to take risks, he needed to fight for what he wanted. And he did.
“A man unwilling to fight for what he wants deserves what he gets”
(quote from another show, but that fits perfectly here)
And things actually worked. Liv’s smile when she realizes Lincoln chooses to stay with her, that Lincoln chooses her above his own world, says it all. She wanted the same as him.
I don’t think they started dating right away. My headcanon says they spent a good time as friends and coworkers, getting to know eachother and for Lincoln to adapt to this new world. Even despite his desicion, it must have not been that easy to let everything in his previous life behind. I think they took the time to fall in love, but it was inevitable, and probably they both knew it from the moment the bridge closed, that they would end up together.
Wow, this was really long, sorry about that. I just love to talk about Lincoln and Linham, as you can see.
And now I gave me Linham feels again. (not that the feelings ever go, anyway..)

He needs you. That’s very me.
Lincoln and Liv (Linham) - Safe and Sound
Basically, I turned part 7 of the “Meanwhile in the Redverse” series into a vid.
Watch in HD please. Hope you like it :)
You also can watch directly on youtube, here.
New Linham vid coming later ;)
NO BUT REALLY. THERE WAS A TIME WHEN LINCOLN COULDN’T IMAGINE SOMEONE GIVING HIM THAT LOOK TO HIM.
HE MAYBE THOUGHT HE WOULD NEVER KNOW LOVE LIKE THAT.
BUT HE DID. LIV LOOKS AT HIM THAT WAY.
HE FOUND LOVE.
HE FOUND HOME.

“Robert and his wife Julie had this incredible relationship. The way she looked at him… Olivia looks at you that same way”