Dragon Fantasy: Book I

Missable. After escaping the castle basement and talking to the Queen, you can recruit Punchy and Casty from the recruitment center (top left building in the city of Wester).

Serps can be recruited in the inn of Derwent (the town next to the Woodman's shack.) He's the character wearing the black shirt.

Must be done after Man of Shadows if you want to do it on the same playthrough. If you miss it, you can try for this in a new playthrough in about 20-30 minutes. (credit to Loko4FourLoko for the info.)