Books with very introspective, cynical protagonists who live mostly in their head and struggle to connect with others

I’m looking for novels with a protagonist very similar in personality and mindset to Georgia “George” Lass from Dead Like Me.
Someone introverted, emotionally detached, apathetic, sarcastic, and cynical — the kind of character who mostly lives inside their own head, with a strong internal monologue.
Socially disconnected, with few or no close friends, more of an observer than a participant, and someone who deliberately keeps expectations low to avoid disappointment.
I care much more about the character’s inner life than the plot. I’m looking for that detached, existential vibe.