I was going to put this in that post from last night but it got WAY too long for a silly joke post so it's it's own thing now!
To me, YOU falls head over heels for her pretty fast, a life of loneliness making them grow extremely attached to the one person to ever call them a friend super fast. She makes them feel wanted, especially with how she responds to Lancer in the field. Attempting to kill Lancer not only for them, but to essentially "keep them safe" from him in a way. And with the scene where she begs them to end her we can see how it impacts YOU a few rooms later in the shop of The Lodge: they view it as her placing trust in them; and they do want to help her. While the gift is the main driving force for them killing her in The Lodge I genuinely believe it also comes from a place of wanting to help her, to relieve her. They understand her suffering more than ever at that point, the effects of The Gift in full swing.
I also think they would both be absolutely desperate for closeness. YOU, having been isolated their whole life and never experiencing it and Susie going from being neglected, to having friends, to being alone again because of the gift. I really do think they'd come to the conclusion that they're all they have left.