One plot idea could be that Buffy Dawn's transformation into a demon is caused by a dark spell cast by an old enemy. As a demon, she has to struggle with new instincts while her friends try to find a way to reverse the transformation. Another could be that she turns into a demon to gain power to fight an even greater evil, but then has to deal with the consequences of that power.
Not really. While there might be a few 'Buffy Suicide Fanfic' out there, they are not common. The Buffyverse is known for its action, magic, and complex characters. Most fanfic writers are interested in expanding on these elements rather than delving into such a distressing and controversial topic. Also, many fanfic communities have rules against writing about topics like suicide in a way that could be harmful or triggering.
Buffy began as a television show and only later was adapted into comics. So, it wasn't a comic initially. The TV series gained popularity before the comic adaptations came out.
Buffy's relationship with Spike in the comics varies. Sometimes they have significant interactions and may even be romantically involved, but it's not a constant throughout all the comic series.
The more understanding friends would try to find a way to help her. But there would be a lot of tension. For example, if she had a romantic relationship before, her partner might be torn between loving the person inside and being repulsed by the demon form. Communication would become difficult as she might not be able to control her new demonic impulses and might lash out at them.
Probably 'The Gatekeeper Trilogy'. It has been highly regarded among Buffy fans. It has a complex and engaging plot that unfolds across the three books. The trilogy really delves into the lore and magic of the Buffyverse, which is part of what makes it so popular.
I'm not sure if it's a popular work. There are so many Buffy fanfics out there. It might be well - known among some fans who are interested in stories about burglars in the Buffy universe, but without more research, it's hard to say for certain.