(!) May contain headcanon!

Spoilers!!

Jonathan Joestar (ジョナサン・ジョースター , Jonasan Jōsutā) is the protagonist of Phantom Blood and the first JoJo in the JoJo's Bizarre Adventure series.

The son of George Joestar I, Jonathan is an honest, kind, and positive man whose life is filled with tragedy after meeting his adoptive older brother, Dio Brando. In his battle against Dio, Jonathan becomes a Ripple user under the tutelage of Will Anthonio Zeppeli.

Source: https://jjba.fandom.com/en-us/wiki/Jonathan_Joestar