Angel (1999) - 1x08 - I Will Remember You

When Angel tells Cordy and Doyle that he did not contact Buffy during his visit to Sunnydale, Buffy pays a visit and expresses her displeasure. Sparks fly. As they are about to part their separate ways, a medieval demon charges into Angel's office and a violent brawl ensues.

The demon escapes, and Buffy and Angel decide to pursue it separately. When Angel makes contact and kills him, he observes that he has human characteristics. The Powers that Be confirm that Angel is indeed human again. Angel pursues Buffy and they share a passionate night of romance. But the next day, they are confronted by a stronger version of the medieval demon, and Angel is unable to fight in his human form.

After hearing that Buffy would perish if he were to remain human, he begs the Powers That Be to transform him into a vampire so that he can protect her. They do so, and Angel breaks the news to a heartbroken Buffy. However, their blessed reunion will remain only in Angel's memory.