@Omegastyle
US courts in particular apply a distinctiveness test to characters to determine whether they can qualify for copyright protection. If a character isn’t sufficiently distinct, it doesn’t quality. Individual pieces of art depicting that character qualify for copyright protection but the character itself cannot be protected as a distinct entity. It can, however, be trademarked, but trademarks are expensive and require active legal protection in order to retain the mark.
Hasbro doesn’t own your character. Strictly speaking, nobody owns your charcter. In realistic terms it isn’t an issue 99% of the time as most people will generally apply common sense to the matter and acknowledge your defacto ownership of the character, but you can have no legal recourse to protect your character from exploitation by other parties.
This is ignoring the mushy grey area of copyright and fanworks in general. By and large, worldwide copyright law has been moving in a general direction of allowing greater fair-use rights of copyright and trademarked characters for non-profit or derived works on the level of fanfiction and fanart. What test cases exist have broadened the scope of the individual’s right to make derivative works of other IP, as long as they are not directly impacting the IP owner’s ability to exploit their own property.
tl;dr it’s all a bit squishy, but you can’t demand legal protection of your character unless they’re sufficiently distinct. Characters that are created as parts of derivative works generally aren’t sufficiently distinct.