Catalyst

Catalyst
Arthur Petrelli takes the catalyst from Hiro.
First mentioned:	The Second Coming
Owned by:	formerly Ishi Nakamura (deceased), formerly Hiro Nakamura (stolen), formerly Arthur Petrelli (deceased)
Current status:	Extinguished

The genetic modification formula has a third part known only as "the catalyst" and "the light".

About

The Second Coming

Hiro finds a DVD of Kaito. In the DVD, Kaito addresses Hiro and tells him about the formula, which Hiro must protect. He also mentions that there is a "light", which is referring to the catalyst.

It's Coming

While testing the formula, Mohinder and Arthur contemplate why their tests have not been successful. Mohinder realizes that there must be a catalyst that bonds the formula with one's own DNA.

Later, Angela Petrelli says that Kaito Nakamura was protecting the catalyst, and that it was in fact a human being.

While with Peter, Matt, Daphne, Nathan, and Angela, Claire talks about the fact that Sylar told her she was more special than the others and concludes that she must be the catalyst.

The Eclipse, Part 1

Arthur, believing Claire to be the catalyst, sends Sylar and Elle after her.

At the same time, Angela tells Claire that she needs to stay in hiding, and that Noah will protect her. The two go to The Canfields' home and Noah trains Claire to fight. Elle and Sylar find them but Noah manages to incapacitate them before they take Claire.

Our Father

Hiro and Claire go to the roof of the Deveaux building, to witness Kaito handing Claire to Noah. Later, Hiro learns through a conversation between Kaito and Ishi that Ishi is the catalyst. They both know that she will die soon, and Kaito wants her to give the catalyst to Claire.

Meanwhile, Claire goes to see Sandra, who has just adopted Claire's younger self. Claire pretends to be from another apartment and wants to babysit herself. When Noah comes home, he becomes angry at Sandra for letting strangers into the house, as it could violate their assignment. Claire accidentally lets incorrect information slip and Noah discovers that she does not actually live nearby. Claire stops Noah from answering the phone call that she knows will result in herself becoming the catalyst, instead telling Noah that the baby will end up becoming more than an assignment to them, and she will grow up and live with them for sixteen years, possibly more.

After Kaito leaves, Hiro goes to see his mother. Using her ability, she heals his memory and he remembers how much he misses her. Hiro says that he is ready and she gives him the catalyst. However, the transfer is too much for Ishi's body and she dies immediately.

Later, Claire and Hiro are both back on the Deveaux rooftop when Arthur teleports there. He telekinetically pushes Claire away, then using his ability, takes both Hiro's power and the catalyst.

Arthur uses the catalyst to perfect the genetic modification formula. The formula is injected by Mohinder into Scott, as Nathan and Tracy look on.

Later, Peter shoots Arthur, but the bullet is stopped by Sylar. When he finds out that Arthur is not actually his father, he lets the bullet continue on its path, killing Arthur and destroying the catalyst.

Notes

• It is unknown whether Dr. Zimmerman used a catalyst when he gave Nathan, Tracy, Niki, and Barbara abilities.
• In a question and answer session, writer-producers Joe Pokaski and Aron Coleite confirmed that if the catalyst's host body dies, so does the catalyst. Thus, when Arthur died, so did the catalyst.

Gallery

• 
  Ishi transfers the catalyst to Hiro...
• 
  ...and he glows in the process.
• 
  But Arthur soon takes it from him.
• 
  Arthur transfers the catalyst...
• 
  ...into the formula.
• 
  The formula is now complete.
• 
  The catalyst dying with Arthur.

Fan Theories

Please refer to Theory:Catalyst for fan-created theories and other speculation.