Padmé would be devastated. She loved both Anakin and Obi - Wan. Her relationship with Anakin would become extremely strained, if not completely broken. She might try to stop Anakin from further falling into the dark side or, in her grief, turn against him.
Yoda would be deeply saddened and disappointed. His relationship with Anakin was already tenuous due to Anakin's struggle with the dark side. After Anakin kills Obi - Wan, Yoda would likely see Anakin as a lost cause and focus more on protecting the remaining Jedi and the galaxy from Anakin's wrath. The other Jedi would also be in shock. They would feel a great sense of loss for Obi - Wan and a great fear of Anakin. Some might want revenge, while others might try to find a way to redeem Anakin, but overall, the unity among the Jedi would be severely shaken.
The clones, who had a certain level of respect for both Anakin and Obi - Wan, would be in a difficult position. If they were still under the influence of Order 66, they might side with Anakin, but those with a stronger sense of morality might question Anakin's actions. Their loyalty would be split, and this could lead to internal conflicts among the clone troopers. And for characters like Ahsoka, who was Anakin's apprentice and had a strong bond with Obi - Wan as well, it would be a heart - breaking situation. She would have to grapple with her loyalty to Anakin and her love for Obi - Wan, and this could set her on a path of self - discovery and a search for justice.
The presence of a child would likely make their relationships more nurturing. Female Obi - Wan might take on a more motherly role towards the child, and Anakin and Ahsoka would be influenced by her example. They would become more protective of each other as they are all responsible for the child's well - being.
Some fanfictions might explore a situation where Anakin is being manipulated by a powerful dark force or a Sith Lord. This dark influence makes him see Obi - Wan as a threat to a grander plan. So, he kills Obi - Wan as part of this dark scheme, not fully in control of his own actions. And this can lead to a lot of complex emotions and plot developments later in the story, like Anakin's further descent into darkness and how the other characters react to Obi - Wan's death.
In some fanfictions, the relationship could be one of mentorship. Despite their initial differences, Anakin could recognize the potential in Obi - Wan's son. He could teach the son things that Obi - Wan couldn't, using his own unique experiences. And the son could provide Anakin with a sense of purpose and a new connection to the Jedi way, helping Anakin to move away from his dark past.
It could either strengthen or weaken their relationship. If Anakin discovers something noble in Obi - Wan's past, like a great sacrifice he made, it might make Anakin respect him more. But if he uncovers something that he perceives as a deception, like a hidden mission or a relationship that Obi - Wan kept from him, it could lead to mistrust.
Their relationship might start with suspicion. Obi - Wan would be cautious as he's seen Vader's evil deeds. But as Vader is suitless and perhaps more 'human' in a sense, Obi - Wan could start to see the Anakin he once knew. This could lead to a slow rebuilding of trust.
It changes Harry's view of Snape completely. Harry already had a very complex relationship with Snape, but this act would make him see Snape as an even greater enemy. He would be filled with rage and a thirst for revenge. Hermione and Ron would also be very affected. They would support Harry in his quest to avenge Dumbledore and would see Snape as a traitor to the wizarding world.
Perhaps Obi - Wan uses his Jedi skills in a creative way. For example, he could use a Force - related technique that shields Anakin from the influence of the Sith. He might create a sort of Force barrier around Anakin's mind, preventing the dark whispers from corrupting him further.
Maybe the Force itself could be an antagonist in a sense. The light side of the Force would be trying to pull Obi - Wan back from the dark side. And the natural balance of the Force that doesn't want too much dark side influence could be working against Anakin's plan to turn Obi - Wan. So the Force, in its own way, could be the main antagonist.
Female Obi - Wan might develop a more nurturing side. Instead of the more stoic Obi - Wan we know, she could be more openly affectionate towards Anakin and Ahsoka. Anakin, with this different influence, might not be as quick to turn to the dark side. He would have more emotional support. Ahsoka would grow to be more confident, as she has two strong role models in Female Obi - Wan and Anakin. She would be able to learn from their different styles of using the Force.
The most obvious implication is the destruction of Obi - Wan's world. Obi - Wan would be devastated and likely turn all his efforts towards revenge. This would change his character from a calm and collected Jedi to a more vengeful figure.