Say a guy creates a Patreon for his brother who is a video game designer. A lot of people love his games and he's popular in the community. The guy does not imitate his brother, but instead claims that money donated will be split with him -- however, his brother has no agreement/idea with this.
The Patreon owner would not be stealing from his brother per se since the money sent is to be shared with him whether he knows it or not -- and there's no copyright infringement/intellectual property issues/etc. Given these specifics, would it be illegal to collect Patreon money on behalf of another person's work expectancy, regardless of whether they choose to accept or even know of it?