Drelas can follow the player outside and can get caught up in a fight with the dragon found near this location.
Drelas can represent a difficult opponent for low-level players, so caution is advised.
When entering his cottage during daytime, he will likely be hunched over the Arcane Enchanter in the corner, with his back to the door. With a high enough Sneak skill or potion, it may be possible to perform an initial sneak attack.
It is best to use lightning spells to damage his magicka pool.
Drelas will often retreat upstairs and attempt to heal himself, so a good strategy is to use a Magicka Poison during the initial attack.
Drelas does not respawn.
If Harmony spell is used on him (he's too powerful for low-level Calm spells), he will speak trespassing NPC lines like "You're not supposed to be in here."