Sesshomaru would first of all, ensure that Rin has a proper place to rest and stay. He would probably use his influence to get the best possible resources for her. He might not be very expressive verbally, but his actions would speak volumes. He would hunt for the finest food for her, and when it comes to any difficulties or fears Rin has, he would be there to listen and offer his unique perspective. He would also be vigilant against any potential harm that could come to her or their unborn child, using his combat skills and strategic mind to keep them protected.
Shirou would likely be very practical in his support. He'd make sure Saber has proper nutrition, cooking her healthy meals. He'd also take on more of the household chores so that Saber can rest. For example, he'd do the cleaning and laundry without hesitation.
Tony would likely use his wealth and technology. He might create a special medical facility in their home to ensure Pepper has the best prenatal care. He could also design a suit for Pepper that provides extra comfort and support during her pregnancy, like having built - in massagers for her backaches.
He could take on more of the household chores. Since Misaki might be feeling tired or unwell at times, Usui would cook for her, clean the house, and do the laundry to make her life easier.
Finn would probably be very protective. He might stand guard outside her resting place and keep a lookout for any potential danger. Jake, on the other hand, could use his shape - shifting abilities to make things more comfortable for Lady Rainicorn, like creating soft beds or warm blankets. Princess Bubblegum might use her scientific knowledge to make sure Lady Rainicorn has a healthy diet and proper medical care.
Anakin would likely use his Jedi skills to protect Padme. He'd be constantly on guard against any threats. He might also use the Force to sense if Padme or the baby were in distress. For example, if Padme was feeling unwell, he could use a gentle touch of the Force to soothe her. He would be her emotional rock too, listening to her fears and hopes for the future of their family.
Their relationship would likely become more protective. Sesshomaru, being a powerful demon, would be extremely vigilant about Kagome's safety and the safety of the unborn child. He might not show it in the most obvious ways at first, but his actions would speak volumes. For example, he would be more likely to stay close to her or send his minions to guard her when he couldn't be there.
Gru could support Lucy by doing household chores for her. Since she was pregnant, she might be tired easily. So things like cooking, cleaning, and doing the laundry would be great help.
Naruto would support Hinata by being there for her emotionally. He would listen to her concerns and fears about becoming a mother. He'd also be physically present as much as possible, helping her with daily tasks like carrying heavy things.
Well, it depends on the specific fanfiction. Some authors might choose to include a kiss between Sesshomaru and Rin as a way to show the development of their relationship. But not all fanfictions will have this. There are many fanfictions that focus more on their platonic bond or other aspects of their characters. For example, some might explore Sesshomaru's growth as a character through his interactions with Rin without getting into a romantic kiss.
They can offer practical help like running errands for the pregnant person. Buying groceries or picking up medications are simple tasks that can make a big difference.