Future Past

 Ryak sends three western outlaws to warn Choi of an impending catastrophe that will threaten the time stream but they fail to carry out his orders so Ryak causes their heads to explode. Ryak tells Choi that Professor Hyatt is a chronal terrorist who has stolen something from the time stream and has made the Linear Men's perception of time erratic. Ryak tells Choi that when he gets in contact with Hyatt then he must contact the Linear Men by speaking Ryak's name but if Choi refuses to cooperate then Ryak promises to erase Choi from existence. 

The next day after Choi's class, Choi gets a suprise visit from Dr. Hyatt. Hyatt explains the legacy of his father and how he worked with Ray Palmer during his stay at the university in Ivy Town. Hyatt's father discovered the existence of a time portal or time pool, a singularity that can open any chronological point in time but only Ray Palmer could enter the portal because the temporal event was microscopic. However, when Ray left Ivy Town, Hyatt's father was left to be the only guardian of all human events. 

One day before Choi came to Ivy Town, Hyatt's father had disappeared. Hyatt assumed his father had gone mad from the burdening responsibility of keeping the time portal safe so he must have jumped in somehow. Hyatt had no other choice but to swallow the microscopic time portal in order to travel the time stream and rescue his father. Unfortunately, the portal caused half of Hyatt's body to transport to the future while the remaining half remained in the present but what was astounding is Hyatt was still alive even though he wasn't completely whole.  

During their conversation, Ryak attacks the two professors and Hyatt reacts erratically by transporting himself along with Choi to the point in time where the other half of Hyatt's body is. Choi is shocked that the future of Ivy Town has been heavily influenced by the achievements of the Atom. Choi also notices a statue of his former girlfriend Jia and she bares his last name as well as an Atom costume. Ryak arrives and subdues Choi so he can explain what has happened. Unbeknownst to Choi, Teddy Hyatt doesn't actually exist, he is simply a juvenile construct of the actual Prof. Alpheus Hyatt.  

 The youthful half that Choi has been assisting is part of Hyatt's disturbed mind which has been suffering from senile dementia. Hyatt has been demonstrating symptoms like mental illness, aphasia, involuntary tremors and mental loss. The older yet lucid half of Hyatt tried to rejuvenate himself by swallowing the time pool but instead it was sent to the future. Ryak agreed to restore the time stream and dismiss all charges against Hyatt if he gave the time pool to the Linear Men. Once all was said and done, Hyatt was returned to his natural age but his mental condition would naturally get worse over time.