Dr. Michael Gehabich is a character in the anime Bakugan Battle Brawlers. He is the grandfather of Alice Gehabich. Similar to how Alice can become Masquerade, he also has a negative split personality in the form of Hal-G, as whom he is seen as for the majority of his appearances in the anime. He first developed Hal-G when a large amount of negative energy from the Silent Core infiltrated his lab. After Naga was defeated by Drago, Hal-G left his body and Michael returned to his normal self.
Dr. Michael invented the Dimensional Transporter System where humans can allow to transport to another place or world. One day, Michael accidentally opened a gate to Vestroia during a test, in which he transported to Nova dimension. While transporting, the phenomenon that caused cards to fall from the sky back in Earth happened as result of Naga's attempt to get the cores and the different flow of time in Vestroia caused him not to witness this event. When he arrived, Naga appeared in front of him, amazed that he sees a human entering Vestroia. Naga asked him for a way to get into the center of Vestroia (since he cannot enter it by normal means) and he gives the card to him (Drago witness this conversation), not knowing its true motives. Naga then blow Michael away back to Earth,and when he returned, he realized that a half year has passed since his visit to Vestroia. At thid point, the children made a game called Bakugan from the creatures that transported from Vestroia through cards.
After his return, he goes to Alice's house to see her, and when she shows the card, he was amazed and starts to do further research on Bakugan, from how they are transported to Earth to their capabilities in battle. He decided to record his research in a video diary and while recording, he was interrupted by Alice. When she suddenly notices that someting is wrong in the Transporter System, the negative energy burst caused by Naga, who was absorbed by the Silent Core (this phenomenon is called Super Dimension Nova (スーパーディメンションノヴァ, Supa Dimenshon Novua?) in the Japanese version) oveŕflows into the lab and caused Dr. Michael and Alice to transform into Hal-G and Masquerade, respectively.
By that point, he becomes absent for most of Season 1, being only seen in flashbacks in some episodes like The Story of Vestroia or in a picture in Girls Just Wanna Have Fun where Drago recalls his conversation with Naga. His body becomes possessed by Hal-G for most of the season.
He finally made an physical appeaeance the first time in R Is For Revenge at the end of the episode. In Showdown in Wardington, he returns to his true self, ableit breifly, telling to Alice that he needs the Positive Energy from Wavern to heal himself. Hal-G then used this advantage in The Good, The Bad & The Bakugan to get Silent Naga closer to Wavern. After Hal-G expelled from Michael's body, he returned to his true self completely, which Alice become happy. He then returned to Moscow with Alice at the end of Season 1.
He is first seen in Moscow with Alice, fixing the gate to New Vestroia. When he tests it by sending a Russian doll, it fails to teleport. He tries once more with a Gate Card and it teleports successfully. However, unknown to him or Alice, it sent thousands of Gate Cards into New Vestroia, one which is caught by Spectra and given to Professor Clay. Later, Michael used the technology of Lync's gauntlet to fix the gate thus preventing Alice, Runo, and Julie from going to New Vestroia along with Dan and Baron, as they did not have gauntlets which were required to be able to enter.
Later, Klaus von Hertzon reveals that he worked with Dr. Michael in rebuilding the dimensional transportation by funding the project and to mass-produce the device. This explains how Klaus made it to and settled in on Vestal.
Hal-G (Alter ego of Dr. Michael)