Both are lovely!!
Both go with [name_m]August[/name_m] well too in my opinion.
Haven’t met a [name_m]Leon[/name_m] yet, but I have met a Spanish [name_m]Sebastian[/name_m] who went either by [name_m]Sebastian[/name_m] or [name_m]Sebas[/name_m]. Haven’t met a [name_m]Sebastian[/name_m] called [name_m]Seb[/name_m], but, sounds like I’m in the minority there. There’s Sebby too. But [name_m]Tian[/name_m] is really cool and it’s possible your kid might just keep [name_m]Tian[/name_m] as his nn. I would given the heritage, but, you never know.
I’m not into astrology or horoscopes, so I didn’t know about [name_m]August[/name_m] and [name_m]Leon[/name_m]. Leo/Leon is the same thing to me as both mean [name_m]Lion[/name_m].
This is such a hard pick!!
If [name_m]August[/name_m] is old enough, you could let him do the honors.
Either way fits and is gorgeous. Can’t go wrong with either.