Assuming his backstory stays the same as what Viv has said in the past; Then my headcanon is that his only attachment was to his mother and he was do devastated by her death that he went full "cant get hurt if you dont ger attached".

Vox is gonna convince him he has Charlie and going to trade 'her safety' for Lucifer being captive. Totally prevents Lucifer from poofing away and also means its the same conditions for both Lucifer and Alastor getting loose.

Very tsundere coded.