Honestly if I were DMing and a PC tried the "best, most loyal friend" wish. . . I'd be thrilled. I'd probably waive the chance of losing access to wish. That player would be handing me a free adventure hook, complete with railroad tracks. Choo choo! Next stop, the past!
It really is the perfect setup for a time-travel adventure. Let them pre-visit familiar locations, see very old NPCs when they were young, plant the hook for an adventure they already completed, seduce each others' ancestors, etc. The wish requires the PC to befriend the young Tarrasque and go on at least one (1) cool adventure together - or they're trapped in history forever.
Personally, I'd make the "befriend" part tough as hell. Go deep into the bowels of the world where great powers are conspiring to use the young beast for various purposes, and all stand ready to thwart the PCs. The "cool adventure" prong can be a softball power fantasy where the PCs get to just rampage. Maybe it's a guilt-free slaughterfest of the cold, soulless undead. Maybe you make a custom creature that's very evil and nasty and let the PCs drive them to extinction. Maybe a rival's ancestors are involved and the PCs can kill a lookalike grand-uncle and pick up old family secrets for blackmail.
Then back to the present, the wish fulfilled. The Tarrasque wiggles excitedly in recognition, wreaking havoc. The PCs can calm the Tarrasque until it can be made comatose again, or take it back deep into the world and tell it to stay there, or decide it needs to be put down after all and start over, or whatever.
Honestly if I were DMing and a PC tried the "best, most loyal friend" wish. . . I'd be thrilled. I'd probably waive the chance of losing access to wish. That player would be handing me a free adventure hook, complete with railroad tracks. Choo choo! Next stop, the past!
It really is the perfect setup for a time-travel adventure. Let them pre-visit familiar locations, see very old NPCs when they were young, plant the hook for an adventure they already completed, seduce each others' ancestors, etc. The wish requires the PC to befriend the young Tarrasque and go on at least one (1) cool adventure together - or they're trapped in history forever.
Personally, I'd make the "befriend" part tough as hell. Go deep into the bowels of the world where great powers are conspiring to use the young beast for various purposes, and all stand ready to thwart the PCs. The "cool adventure" prong can be a softball power fantasy where the PCs get to just rampage. Maybe it's a guilt-free slaughterfest of the cold, soulless undead. Maybe you make a custom creature that's very evil and nasty and let the PCs drive them to extinction. Maybe a rival's ancestors are involved and the PCs can kill a lookalike grand-uncle and pick up old family secrets for blackmail.
Then back to the present, the wish fulfilled. The Tarrasque wiggles excitedly in recognition, wreaking havoc. The PCs can calm the Tarrasque until it can be made comatose again, or take it back deep into the world and tell it to stay there, or decide it needs to be put down after all and start over, or whatever.