Doing the mage path will give you a little boost from Leliana and Wynne. This is the path to get the blood mage specialization though, so keep that in mind. Leliana doesn’t approve either naturally, although she isn’t as angry as Alistair. Killing Isolode to get into the fade will greatly anger Alistair (you’ll lose ten) even if he isn’t with you. You can justify it to Alistair by saying it was your only real option and that he was doomed anyway. Killing Conner is a straightforward way to do it.
Note that this will play out the same as if you did the blood ritual. If you allied with the templars, then this just isn’t an option. Nothing will change in the castle since the Demon is out of followers and they’ll keep Conner at a distance from everyone upstairs. If you haven’t allied with the mages yet, then you can go ask for their help now. You can also call on the Mages to do the ritual instead and they won’t need a blood sacrifice. Isolode will give up her life to send a mage into the Fade to kill the demon there. If you didn’t kill Jowan (and I told you to keep him alive) then you can bring him up through the first conversation and he’ll explain the blood ritual.
This will end up killing him though, and you are killing a little boy who just wanted to save his father…so yeah. You can just kill Conner to take the demon out with him. Your decision will naturally have a few effects too. There are two different ways to fight the demon and three different paths.
