Element Lad

 Pre-Zero Hour

With the aid of the Legion, Roxxas was brought to justice and Jan joined the Legion, using the codename Element Lad.  He was a member of the Legion for many years, serving terms as leader and deputy leader.  He was romantically linked to Shvaughn Erin, the Science Police's Legion liaison, who was depicted as a transsexual later in the series.  When Shvaughn was forced to revert back to being a man, Element Lad revealed he stayed with 'her' all this time not because of 'her' being a woman, but despite it.

Earth-Prime

In Mark Waid and Barry Kitson's reboot of the 31st century, Element Lad was once again a core member of the Legion of Super-Heroes.  His power included transmutation of elements through touch, although the transmuted object(s) would revert back to their original chemical compositions after a minute.  Jan's reasons for joining the Legion were that he saw them as a nexus of great change, something all Trommites would have appreciated.   Chameleon mentioned that Element Lad was the sole survivor of his planet, Trom, although that was never elaborated on.

Some of the Legionnaires, Element Lad included, aided Brainiac 5 in his resurrection attempt on Dream Girl, although Jan was personally against the idea.  The attempt seemed to have failed when Dream Girl's body dissappeared, and Element Lad unsuccessfully tried to convince Brainiac to let her go.

This version of Jan Arrah has been shown to be greatly fascinated of change, and also displayed a strong dislike for physical violence.

Final Crisis: Legion of Three Worlds

Like every active Legionnaire of his world and Earth-247, Element Lad was transported to the 31st century New Earth, to help the present Legion combat Superboy-Prime, and the Legion of Super-Villains.

When Sun Boy was murdered by Superboy-Prime on New Earth, Element Lad decided to put his qualms about violence aside to avenge his friend.  He managed, notably enough, to create kryptonite that Superboy-Prime showed to be vulnerable against (he had earlier been immune to the radioactive substance, due to Kryptonians only being affected by kryptonite from their respective universes).  In his rampage, Prime responded by launching one of the kryptonite rocks through Element Lad's torso, killing him.  A while after Prime was defeated, Brainiac 5 of New Earth explained that the reason Prime was vulnerable to Jan's kryptonite, was that Element Lad and his Legion were from the reality of Earth-Prime themselves. 

During the events of Legion of Three Worlds, the Element Lad native to the New Earth universe (supposedly the same as the original, pre-Crisis version of him) had been reported as missing.  The Legion had not heard from him since the start of Earth-Man's xenophobic campaign.
 

Legion of Three Worlds Aftermath

Adventure Comics #1 revealed that New Earth's Element Lad is undercover as Smallville high's science teacher. The purpose of this is unknown but he teaches Simon Valentine and Connor Kent. He is joined in the 21st century by Tellus.