Tropes present in Halflife include:
- Attention Deficit... Ooh, Shiny!: Trix.
- Awkwardly Gay Dream: Played with. Fitz dreams he and the Doctor are naked and back to back, and the Doctor reassures him it doesn't necessarily mean anything about his sexuality. However, any hint of eroticism is quickly lost when they start melding together. It turns out to be a sort of manifestation of the "Freaky Friday" Flip they're about to go through.
- Bear Hug: The Doctor hugs Fitz in a way described as "rib-cracking".
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Best Known for the Fanservice: This book is most well-known for the Doctor/Fitz naked bum rubbing dream. - Elephant in the Living Room: Pretty much how Fitz feels about the Doctor's arse after getting to know it a bit too intimately.
- Fan Disservice: Around when they start melding together...
- Forgets to Eat: The Doctor, at the beginning, due to the events of the previous book.
- Have I Mentioned I Am Heterosexual Today?: Fitz.
- Heroic BSoD: The Doctor at the beginning.
- Innocent Fanservice Guy: Since the Doctor doesn't really grok nudity taboos, all of a sudden Fitz doesn't either.
- Must Have Nicotine: The Doctor, to his surprise.
- O.O.C. Is Serious Business
- Out-of-Clothes Experience: That infamous naked-bum-rubbing dream again.
- Personality Swap: Fitz and the Doctor.
- Sesquipedalian Loquaciousness: When he's got the Doctor's personality, Fitz becomes a lot more comfortable with words of more than five syllables.
- Tears of Remorse: The Doctor realizes that Fitz is generally terrified during their adventures, and feels very guilty about being the main cause of it.
