The Seelie Queen could be an antagonist. She might see the unborn child as a threat to her power or a valuable asset to control. So, she could try to manipulate Magnus and Clary throughout the pregnancy.
There could also be some rogue warlocks who are jealous of Magnus and his relationship with Clary. They might see the pregnancy as an opportunity to get back at Magnus. They could try to cast harmful spells on Clary or the unborn child, or they could try to drive a wedge between Magnus and Clary during this vulnerable time.
Valentine's followers who still hold grudges or want to use the baby for their own dark purposes could be antagonists. They might try to kidnap Clary or find a way to harm the baby. They could create various obstacles for Magnus and Clary during the pregnancy, like spreading false rumors or causing trouble in the Downworld to draw their attention away from protecting the baby.
It can lead to all sorts of interesting plot developments. Maybe it causes confusion or brings them closer together.
Maybe it's a new character introduced just for this plot twist. This would add an element of mystery and new drama to the story.
Another option is a group of demons who have a vendetta against Clary or the shadowhunters in general. They might use torture as a way to break her spirit and gain information about the shadowhunters' defenses.
One idea could be that Magnus and Clary discover the pregnancy unexpectedly. They then have to deal with the reactions from their friends and family. Some might be overjoyed while others could be worried about the challenges ahead.
In fanfiction, the Clary and Magnus kiss is often a very passionate and significant moment. It can represent a deepening of their relationship, whether it's a newfound connection or a strengthening of an existing bond. Writers might use this kiss to show the characters' growth, as Clary might be becoming more open to the magical world that Magnus represents, and Magnus might be letting his guard down more around Clary.
The Brotherhood of Mutants could also be antagonists. They might view the pregnancy as a sign of the X - Men becoming too domesticated and vulnerable. They could launch attacks on the X - Mansion in an attempt to disrupt Rogue and Logan's new - found family situation.
Maybe there are some traditionalists in their world who don't approve of their relationship or the pregnancy. These people could be the antagonists, constantly trying to break them apart or cause problems for them.
One potential antagonist could be a group of rogue ninjas who see Sarada's pregnancy as a sign of weakness in the village. They might try to target her to cause chaos. Another could be a jealous rival who doesn't like the attention Sarada is getting due to her pregnancy and her connection to Naruto.
Frieza or his remnants could be antagonists. They might see the unborn child as a potential threat in the future, especially if it has strong Saiyan powers. So they could plan to attack Bulma to prevent the birth.
The Vicious 6 could be the antagonists. They might see Gru's preoccupation with Lucy's pregnancy as a weakness and try to take advantage of it. They could plan to kidnap Lucy to get to Gru and force him to give up his new - found family life and return to his old villainous ways.