The foundational event of Caleb's relationship with MC. Josephine — MC's grandmother, a former member of the Gaia Research Center's Unicorn team — takes Caleb in when he is young, raising him under the same roof as MC. He becomes her older-brother figure. The affectionate nickname 'baby' that he still uses in the present day started here. The exact circumstance of why Josephine took him in is not detailed in the public wiki. His presence in the household is the anchor for all subsequent shared-childhood memories.