Neutral
Neutral (adj & noun) /ˈnjuː.trəl/ US /ˈnuː-/
adj: taking no clear side or position – unbiased – showing no distinctive quality – impartial – pale – colorless, unbiased, disinterested, dispassionate, impersonal
In that argument, I was the only person who was totally neutral.
Antonyms: biased, colorful
Verb: neutralize
Noun: neutralization
Adverb: neutrally