Keeho is 22,amber is 14, agate is 29 and copper is 19

Keeho was the middle child out of the bunch as he was agate's younger brother and the older brother of copper and amber. He's best friends with frisk. Him and frisk were hanging out in Frisk's house as he promised frisk:

"We'll be friends forever! I'll never hurt you no matter what!!"

And frisk chuckled as he promised:

"Same bro, nothing can break our friendship!"