Bay 12 Games Forum

Because that's not the theme here. It's not so much people summoning spirits and binding them as servants, but people coming across them and they decide to work together for whatever reason. Either one of the other or both can have an agenda, and the power boost provided by hosting (and having an ally/friend who can do stuff they can't) helps them further it.

For the partnership to occur, there's a wall of alien-ness and/or prejudice that has to be bridged first, and the hosting thing needs mutual trust to work properly, so friendship and/or mutual self-interest seem like the most likely motives by far.

Yeah, like I said, it needs more development. Currently the major downside is if they host for too long, they burn each other up (when not being hosted, the daemon/spirit/whatever would probably just follow their partner around most of the time). The partnership would probably have some kind of long term effect on both of them, resulting from cumulative effects of multiple hostings, though I have no idea on what those effects should be.