Listen guys I have a crazy theory that explains many things at The Flash. I believe that Barry and Jay are brothers. Probably they are brothers from the same father and that explains a lot of things. First of all, at previous episode we saw a telephone with the contacts ''Dad'' and ''Mom & Dad''. The first contact must be the biological father of Barry (Henry Allen) and the other ''dad'' is probably his Father-In-Law because Henry Allen broke up with his mother by the fact that has another son.
So probably the man with iron mask is Henry Allen father of Jay and Barry and that's explain his interest about Jay at Zoom's lair. Now we know why Earth's one Jay Garrick (Hunter Zolomon) is adopted because Henry Allen was in jail and his mother died at his birth.