I thought that I can link video with few scenes of these two for people here who haven't watched the show to just, get the VIBE heheh (some spoilers included ofc)
in nutshell: the human dude is Viren and he is a grey moral (closer to actual black now) high mage who uses dark magic. All humans were banished from magic lands becasuse of said dark magic because it takes lifes of living magic creatures. So, all elves and humans are in state of active of inactive war.
The Elf is Aaravos and he is a banished and imprisoned Archmage Startouch elf, and most likely he was banished because it was him who taught humans the dark magic. He is mischievous as fuck and does everything for motives only he knows
At some point Viren founds a magic mirror which appears to be a magic camera to Aaravos prison, and he, as a normal human hating elves, starts to cooperate with him little by little :D
Enjoy!