R.E.N. Spells Ren
Veteran
How is Stannis the one true king if the Targ kids were always alive
Robert was never the real king and throne still belongs to the Targaryens
#WeComing
Because the Targs lost the throne by conquest.
King's could be exiled after they're overthrown, they don't have to be killed. They're typically killed, since it ensures they'll never raise an army to challenge the conquest again.