 If you liked
Vandread
|
 ...then you might like
Sousei no Aquarion
|
Mecha series filled with action, romance, and drama.
Both of these series involves the fusion of mecha machines into a stronger entity to fight against the enemy. The main character from being zero to hero.
Throughout the series, both main character learns more about themselves and their origin. Of course there is romance, drama, and among other things.