Dark Souls Remastered | Killing friendly NPCs - Oscar, Knight of Astora

Oscar is the very first friendly you encounter in the game. He's the guy who drops the key to your cell, allowing you to escape. He is encountered in the Undead Asylum and provides you the Estus Flask on your first run. In every run, he will also provide you with the Undead Asylum F2 East Key.

If you kill him before he willingly gives you these things, you will simply loot it off of him. There are otherwise no consequences to killing him. He awarded me 100 souls (on NG+).