This might be a good time for us to talk about what these powers of his are.  I've got some ideas from other iterations of this RP, do you have any ideas?  There's the aspect of his self-healing, and the great potential for him to heal others with it, but there should be a destructive component that he probably just hasn't thought to try and access yet.  That's what the leather gauntlets were about.  

I got an idea for how to, I dunno, foster some trust between them.  Lilith might go off to the front of where this rebellion is going on, slay some of the creatures trying to destroy the walls, and she comes back with some minor injuries and Alexander can offer to try and heal them.  It can be a genuine offer or strategic, to gain her trust, that's up to you.