Connor is the biggest glaring difference in Angel and Angelus
Doesn't Angelus say that Connor "creeps him out"? I've always interpreted his avoidance of Connor as telegraphing something about Connor - he's human-but-not, he's the product of perfect despair, he's alien, all of that - a message that, admittedly, gets garbled, but ties into the demon-violence spell working on Connor. Like, hmm. Angelus senses something really different/off/dangerous about Connor.