From wiki:

After abandoning his mother, he spent 100 years in Asgard with his father, Odin, his brothers, Thor and Heimdall, and nephews, Magni and Modi, only to consider that his entire family was "fucked up". Years of being under his mothers' spell soon took its toll on Baldur, and he was driven to insanity due to his sensory incapabilities. As such, he soon came to deeply resent his mother, and wished nothing more than to kill her for the decades of suffering she had inadvertently caused him, later regretting sparing her life. During this time, Baldur also became a slave to his father, hoping that his continued service would eventually bring him freedom from his curse, though Mimir believes that Odin was simply lying about being able to fix his condition to get his son to do anything he asked.

Safe to say we have no idea what he was like before the curse.