You can corrupt him, it just doesn't really do anything outside of give him a faint purple outline.
(not 100% sure how many of these things are necessary, just listing what I normally do)
So, the big one is to have the Memories of Nyx achievement; this is what opens a lot of the 'corrupt' options for random citizens.
You also need to go and collect Echo (the goo transformation thing). When returning from the meteor site, the guard will stop you; I usually fight him because there's another Nyx option to start corrupting him once you win.
Once Abel invites you inside to talk about the whole corrupt meteor thing, tell him that you're embracing the power but you're definitely doing it to protect him. He'll think you're sweet, and you'll get the option to corrupt him. Grats, you know have a glowy Abel.
I'll note the I was sitting at about 100 corruption for the guard and Abel since I was just brute forcing my way through the river to the meteor. This might not be required, but I'll leave it here in case the above isn't enough.