Doctor Helen Cho is a world-renowned geneticist and the leader of the U-GIN Research Group. She was called to assist the Avengers with her research and technology in the war against HYDRA, asking her to treat Clint Barton. Later, she was approached by Ultron who enthralled her to created a new body for him. However, Scarlet Witch undid Cho's control and she managed to corrupt the process of the creation, although Ultron almost killed her for that.
Working with the Avengers
Saving Clint Barton
Cho was called to Avengers Tower by Tony Stark after Clint Barton was injured in a battle against HYDRA. She was invited to set up her equipment in Bruce Banner's lab, where she had worked before and awaited the Avengers' arrival alongside Maria Hill. Once the Avengers arrived, Cho quickly addressed Barton's injuries and had him moved into the lab.
Cho used a machine based on the advanced technology she had developed in Seoul called the Regeneration Cradle to rebuild Barton's damaged skin, saving his life in mere minutes. Once Barton was stable and joking about living forever, Cho explained how the machine worked, greatly impressing Banner and the others watching. When Cho suggested that Barton's own girlfriend would not be able to tell the difference, Barton insisted he did not have a girlfriend. Tony Stark later invited Cho to a party the team was having to celebrate their victory. At first, she declined but changed her mind when she learned that Thor would be attending.
Cho attended the party in the Avengers Tower and stayed behind after many of the guests had returned home. During the after-party, many of the Avengers challenged themselves to lift Mjølnir while Cho watched. They were interrupted by Ultron who attacked the group. Cho found a place to hide behind a grand piano during the confrontation. When a corrupted Iron Legion drone attempted to kill Cho, Ultron signaled for it not to fire and spared her life.
Before long, the Avengers managed to overpower and defeat Ultron, although Ultron's mind disappeared through the internet. The group gathered in Tony Stark's lab where they discussed what they had witnessed. Cho questioned why the design Stark had built had turned against him and watched the Avengers turned against one another as they discussed how Stark and Bruce Banner could have created the being in the first place and what they could do to destroy it. While the Avengers traveled the world to hunt down and destroy Ultron, Cho returned to her lab in Seoul to continue her own work.
While working with her team of scientists on the U-GIN Genetic Research Facility in Seoul, Cho returned to her lab to find Ultron was waiting for her with Scarlet Witch and Quicksilver. He explained to her the reason why he spared her life, foreseeing her usefulness in his future plans and threatened to kill her work staff if she alerted them. Ultron then used the Scepter on her to control her.
She assisted Ultron in building a human-like body for him using Vibranium and her technology from the Regeneration Cradle, which was given life when the gem from the Scepter was placed onto its forehead. When Scarlet Witch touched the Cradle, she saw what Ultron's main goal was, to destroy all human life on Earth. Horrified, she freed Cho from the hypnosis so that she could stop him. Cho recovered her senses and proceeded to disconnect Ultron from the uplink. She was consequently shot with a concussive blast by Ultron while Quicksilver and Scarlet Witch escaped.
While Ultron attempted to escape with the Cradle, Cho recovered from her injuries. Captain America later entered the facility and tended to her wounds; however, she told him about Ultron's plan to use the Cradle, warning Rogers that the Cradle must be recovered but not destroyed as the power inside the Mind Stone had the potential to destroy all of Seoul. Cho survived Ultron's blast and her work gave birth to the Vision, a powerful robot with the mind of J.A.R.V.I.S. who helped the Avengers destroy Ultron.
Back in the Field
Due to her impressive work, Cho was invited to work with the Avengers at their New Avengers Facility after she fully recovered from her wounds. Cho and Maria Hill toured through the new laboratories filled with her team of scientists led by Erik Selvig as they began their work to assist the Avengers.
Cho seems to be a very polite and friendly character. She is selfless; having built the Regeneration Cradle which has the potential to save millions of lives. She has also displayed high levels of courage and quick thinking as shown when she immediately stopped the download of Ultron's programming into the Vision after being freed from his control. She seems to be upbeat and has a very motivated nature. She doesn't seem to be particularly sociable, declining her invitation to the party and only changing her mind when she discovered that Thor would be in attendance. While under the control of the Mind Stone, Cho appears to be enthusiastic towards helping Ultron and was keen to experiment to create Vision.
- Genius-Level Intellect: Cho is one of the smartest humans in the world, rivaled only by fellow geniuses like Tony Stark and Bruce Banner.
- Master Scientist: Being a world-famous geneticist, Cho has tremendous knowledge and unmatched understanding in the fields of cell biology having invented the Regeneration Cradle, a machine that can regenerate skin tissue, something that amazed even the likes of Bruce Banner. Ultron kept Cho alive when he realized how important she could have been to his plans. She also co-created Vision, Ultron's desired body who ultimately became an Avenger.
- Master Physician: Cho could apply her knowledge of cell biology and genetics for healing purposes, having created the Regeneration Cradle and other gadgetry highly useful to the Avengers for medical purposes.
- Bilingualism: Cho speaks her native language, Korean, and fluent English.
- In the comics, Helen Cho is the mother of Amadeus Cho.