☠ - angry/violent headcanon
Balder very rarely allows himself to be angry. This stems largely from his general assumption that his opinions and emotions are of little importance in the greater scheme of things, and he is, therefore, unlikely to express them, particularly if displaying them could at all be considered inappropriate. Anger is foremost on the list of inappropriate emotional responses, as he understands it, and because of this he has spent a lifetime of suppressing this less than desirable feeling. It has built up over time, and though his nature generally grants him an absurdly long fuse, the bomb that goes off at the end of it is one to be avoided. He is one of the few bloodline carriers of the Berserker fury, a condition known in early Asgard as the Oth, and once his anger is triggered, the violent rage that follows may leave bodies in its wake, friend and foe alike.
♦ - quirks/hobbies headcanon
Despite no longer living with Bragi and Idunn as foster parents, Balder still enjoys keeping in practice with his music. He still possesses a lyre that he keeps among his few personal belongings, and when he is certain no one may hear him (as he constantly fears his mistakes will be the only thing an audience would hear) he plays and even composes several pieces on his own. Occasionally and by request (with some cajoling) he will sing at social events, but he is never one to suggest the idea initially, despite how much he enjoys the activity.
∇ -. old age/aging headcanon
It is not until after his death and resurrection, with several close calls following after, that Balder develops the ability to better speak up for himself and speak out against what he sees as unjust without prompting. He learns over time to voice his opinion and be firm in it, considering it valid in itself, and this is in a large part due to his relationships with very vocal women in his lifetime.
Constantly striving to maintain all facets of appropriateness in his life, Balder is forever doomed to be attracted to those women who are wholly inappropriate for him. He forms stronger emotional connections with ladies who determine to break down limitations and encourage him to do so, though this is generally after some common connection has been formed, whether a shared sense of loss and disconnect with his fellow fosterling Amora, or the shared belief in the importance of security and justice he feels with Karnilla, or even in a less romantic sense, his shared sense of duty and loyalty with Sif. His attraction is based on affirming core values and experiences, followed by an expansion to break down boundaries and limitations and extend those values to their full potential. If a lady also happens to be highly inappropriate, sexually aggressive, and an enemy of the state, the more attractive he finds her, but the initial connection of shared values must be made first. Otherwise he is not only wholly uninterested, but he is completely oblivious to any indication of romantic interest.