Ethan's relationship with Summer began at an unknown time before his debut in "Anatomy Park", where their secret relationship is revealed to her family when he confronts her about not responding to his text messages. After having a discussion with Jacob, he revealed that when he was a child, his older brother took him fishing and molested him in the bushes, and "made him feel like a girl", which traumatized him and became the root of much of his anger. Jacob helps help work through his trauma and he reunites with Summer.
The episode's post-credits sequence indicate that a second Anatomy Park is being constructed inside of him. After it is decided that Pirates of the Pancreas attraction he highly favored is not being rebuilt, Rick became furious and hung up on his associates, causing Ethan to question Rick about his payment.
The original Ethan presumably became a Cronenberg in Dimension C-137. In the current dimension, he has the same backstory as he did in C-137.
In the new dimension the alternate Ethan appeared in "Get Schwifty", where he and Summer convert to Headism. During this time, Summer reveals Ethan can play guitar as the two learn the 'Seven Contemplations of the Head' by singing them. He chose to help Summer save her family from being sacrificed by the rest of the Head worshipers.
His relationship with Summer was not addressed in the episode "Big Trouble In Little Sanchez", as Summer became openly interested in Toby Matthews, an attractive popular boy at their school, though they did not move further when Toby discovered her actions resulted in Tiny Rick's expulsion. It is therefore assumed that Ethan and Summer broke up sometime before this episode, and she later had a serious relationship with a man named Hemorrhage in another dimension as well.
Despite this, Ethan and Summer resumed their relationship again sometime before "The Whirly Dirly Conspiracy", and had made plans for a romantic camping trip. Ethan, however, cancelled these plans to instead take a girl named Tricia Lange, although the exact circumstances of their breakup were not seen. Summer is nonetheless distraught and begins to feel insecure about her self-image as Tricia has larger breasts than her. Summer returned home in tears and asked her mother Beth if she was attractive. When Beth refused to answer, Summer tried to use her grandfather's alien technology to adjust the size of her breasts, ultimately enlarging her entirely. Her mother's attempt to repair this makes her inside-out as well.
Upon hearing that Ethan had dumped Summer, Morty confronted Ethan on his camping trip with Tricia. Morty deduced from his conversation with Beth the exact whereabouts of Summer, which turned out to be Camp Flabanabba. Upon arriving to the camp, Beth turns herself into a gigantic monster in the same form as Summer to comfort her. Tricia is emotionally touched and goes home to see her own mother. Morty refuses to allow Ethan to go after her, and instead reminds him of how much he hurt Summer. The episode's post-credit sequence revealed that Morty had grossly disfigured him as revenge for dumping Summer.
Ethan is a slender, somewhat fair-skinned teenage boy with long and wavy blonde hair. He wears a blue hoodie, a white shirt, burgundy trousers and grey shoes with white soles.
In "The Whirly Dirly Conspiracy", he is later grossly disfigured by Morty. After this, his forehead was drastically inflated, reshaping his head. His left ear was also grown to about the size of his original head. His left leg was enlarged and his right arm was elongated forcing him to drag it behind him.
Ethan is a sensitive nature boy but frequently becomes defensive because of his insecurities about his masculinity due to being molested by his brother as a child, describing himself as being made to "feel like a girl". During his relationship with Summer, he was often depicted as seeking her out, such as when she could not text him during the Smith's Christmas or when he wanted to celebrate the new religion, worshipping the heads. Summer and Ethan are also very physically affectionate with one another, including making out in front of her family. He was also willing to help save her and her parents from the displeased Heads. He generally appeared to be rather clingy towards Summer during their relationship.
Despite this, in "The Whirly Dirly Conspiracy", he leaves Summer out of preference for another girl, possibly of her larger breasts, suggesting that he is superficial and cares more about physical appearance and sexual satisfaction more than anything else, when it comes to dating girls.
Ethan and Summer are generally in a boyfriend-girlfriend, relationship that's often interrupted with long-winded arguments that get very personal. In "Anatomy Park", Ethan was mad at Summer for ignoring him and in "The Whirly Dirly Conspiracy", Summer was offended by Ethan caring only about her appearance. They've constantly, broken it off and gone separate ways, with Summer starting new relationships with other boys, but they seem to forget the past and get back together again in future episodes. It can be said that Summer and Ethan keep forgiving each other and denying their past fights.
At the end of "The Whirly Dirly Conspiracy", Ethan appeared to be intimidated by Morty, when he threatened him with a growth laser. Morty horribly disfigured Ethan's body as revenge for breaking up with Summer and thereby causing the crisis.
Ethan dates Tricia in "The Whirly Dirly Conspiracy" shortly after breaking up with Summer and takes her to the camping trip he and Summer had planned to go on themselves. Summer believes Ethan is only dating Tricia Lange because she has large breasts. On their camping trip Ethan seems to be only half listening to her and agreeing with whatever she says. He was disappointed when she ran off to call her mother after witnessing the moment between Beth and Summer.
- Ethan's way of getting physically deformed in "The Whirly Dirly Conspiracy" is similar to the punishment concocted by the genocidal supercomputer A.M. on his human prisoners in the 1967 science-fiction short story, "I Have No Mouth and I Must Scream".