Ohio Flynn is a 1914 archeologist-adventurer, and possibly the ancestor of Phineas Flynn. He took the place of Phineas Flynn for the episode: "Phineas and Ferb and the Temple of Juatchadoon".
Ohio shares many attributes with his (probable) descendent Phineas Flynn, such as a fondness for ice cream, an optimistic personality, a care-free and fun-loving attitude, high levels of creativity and a philosophy of living everyday to the best of one's ability.
Despite these similarities, there is one major difference between Ohio and Phineas. Ohio fancies fame, wealth, and glory, unlike Phineas who couldn't care less about them. Ohio has shown to be more opportunistic than Phineas, seizing what is around him rather than building it. While Ohio aims at wealth, fame and glory, he also seems to enjoy and cherish the adventure just as much.
In addition while Ohio held no grudge against Isabella for her betrayal, he seems to have a personal grudge against Doofenshmirtz.
Another major difference between him and Phineas is that he seems to be easily annoyed, unlike Phineas who is rarely angry or annoyed.
Ohio is very creative solving problems in mere minutes and getting out of fatal traps that older and more experienced treasure hunters couldn't do. He is a very capable archeologist and has vast knowledge of history and mythology.
Rhode Island Fletcher
Ohio and Rhode Island are partners in the world of archeology, and have done at least one job involving a run in with Doofenshmirtz, and/or Candace. Just like their present day counterparts, they seem to be close.
Judging from her editor's reaction to past failures, it is assumed that the Candace of 1914 tried to get proof of Ohio and Rhode Island's adventures at least once prior to the episode. Though these attempts seem to mirror the failures of the modern Candace, the Candace of 1914 doesn't want to stop Ohio and Rhode Island, but report on them.
Doofenshmirtz (1914 counterpart)
Judging from Ohio's recognition of Doofenshmirtz, this gives the illusion that they have had at least one run in prior to the events of "Phineas and Ferb and the Temple of Juatchadoon". Ohio has shown an open distaste towards his nemesis in archeology.
Perry the Platypus (1914)
Ohio showed a shocked surprise at the mysterious platypus for rescuing him and his friends. At the end of the episode, he and Rhode Island both thinks it's odd that they were rescued by an anthropomorphic platypus that wears a fez even though none of them are in Egypt.
Unnamed Buford and Baljeet look-a-likes of 1914
The unnamed Buford and Baljeet look-a-likes of 1914 seem to be on relatively good terms with the dashing duo of Ohio and Rhode Island, it is unlikely that they met prior to "Phineas and Ferb and the Temple of Juatchadoon". Nonetheless, they did save Ohio, Candace, Isabella, Vivian, and Rhode Island from drowning.
Isabella was blackmailed into double-crossing Ohio and Rhode Island for the sake of her mother. Ohio called her a Dirty Double Crosser, which she responded to by giving him a "Dirty Double Crosser Business Card." After they were free, Ohio forgave Isabella.
- Despite every member of the Flynn-Fletcher Family being in the episode, it is unlikely that Ohio is related to them and that their descendents are all related.
- Ohio is the only alternative-Phineas who is more for fame, wealth, and glory than fun, but does seem to cherish fun all the same.