From what I can gather, they more closely resemble modern mercenaries than did the Red Branch of Ulster, which would be more akin to the Royal Army of King Conchobar, i.e., conscripts as opposed to elite soldiers for hire.

So the Hound and his comrades, for instance, would actually live at Emain Macha more or less constantly (except when Cuchullain went home to his wife and estate), while Fionn led his troops about the countryside.

Morgan Llywelyn's different treatments of these characters seem to hold to this position.

A website -

www.shee-eire.com/Magic&Myt.../Page1.htm

And another -

www.timelessmyths.com/celtic/fianna.html

I'll settle back and wait for nitpicking to begin.