the.com/partisan
A person whose team jersey is permanently fused to their reasoning.
means A firmly devoted supporter of a party, cause, or person, often loyal past the point of objectivity.
from From Italian partigiano, a member of a faction, rooted in Latin pars, meaning a part or side — to be partisan is literally to take a part rather than the whole.
Guerrilla cousinAlso means an armed resistance fighter behind enemy lines.
Old weaponA partisan is also a long-bladed medieval spear.
Built-in biasThe word presumes loyalty outranks neutrality by design.