the reason your video game save file has a wise old mentor who used to be the protagonist.
means a returning character from an earlier installment, kept around mainly to cash in on audience nostalgia and hand off narrative authority to the new lead.
from the term migrated from tech, where legacy meant old code kept alive for compatibility, into franchise storytelling around the 2010s reboot boom, when studios realized old heroes could be support systems for new ones without retiring completely.
luke skywalker — force awakens, 2015, reduced to a hermit cameo.
han solo — same film, killed off to anoint a new lead.
sarah connor — terminator dark fate, 2019, returns as grizzled backup.
tony stark — mcu, mentors spider man before exiting the franchise.