When Suze is trapped under the rubble of part of the Missionary Academy's roof near the end of Shadowland/Love You To Death, the moment she hears someone, she (reasonably) assumes that it's Jesse. Her response? For him to get back because it's too dangerous. Jesse is a ghost, can't be hurt by anything that's around here, and they haven't been all that civil in the time that they've known each other. And it's still the first thing she thinks, even over her own safety or comfort.
Whilst going down the cliff to meet up the RLS Angels during Reunion/Mean Spirits, Suze keeps suspiciously checking for snakes in the undergrowth, paranoid abot one rearing up and biting her leg- and all the while she notices that Jesse's perpetually at her side, steering her away when she gets too close to the edge.
In Darkest Hour/Young Blood, Suze has Father Dominic exorcise her soul from her body so that she can go up into the spirit realm and find Jesse, guiding him back so that he can find out what really happened to him and finally rest in peace. However, if he wants to stay, she's decided that although it will hurt, she'll be fine with it. When she gives him the choice, his response is simply, "Susannah, are you telling me that you died for me?!" before realising that she'll be dead soon if they stay much longer than half an hour, and immediately beginning to drag her back. He doesn't even have to think about it.
In Haunted/Grave Doubts a recently-dead ghost insults Suze. Used to it, she could care less. But Jesse? Makes him apologise to the lady.
Later, at the very end and after the Wild Teen Party, Cee Cee calmly says to Suze, "Jesse's a ghost, isn't he?" And in spite of Suze immediately denying it for all she's worth, she still believes it, is very calm about the fact that her best friend can see and talk to ghosts and has a huge crush on one, simply asking that though she can't understand it right now, she hopes that someday Suze will tell her everything. For someone who is very scientifically minded, that's extremely touching, especially when Cee Cee says "For you, I'm willing to make an exception".
Understandably, the meeting between Suze and alive!Jesse in the past in Twilight/Heaven Sent is awkward and fraught with tension. However, after spending about an hour together, alive!Jesse gets past all of the strange, unbelievable and unconceivable aspects of the situation, and a bond immediately forges between them. It may not be the deep love they share in the future, but it proves that they were simply meant to be together- no matter the circumstances.