>>718889103
>>718889272
In Undertale, Gerson is at least as old as Asgore (centuries old, before the war) but isn't immortal/unaging because he's not a Boss Monster
Gerson and Toriel and Asgore probably aren't hundreds of years old in Deltarune. In Deltarune's more mundane setting a very old monster like Gerson would have just died of old age.