Financial difficulties can also be a big issue. Adventures can be costly, and raising two kids is not cheap either. In the novel, the adventurer might struggle to afford both the necessary equipment for adventures and the kids' needs such as clothes, toys, and educational resources.
One challenge could be time management. The adventurer has to balance exciting and often dangerous adventures with the daily routines of parenting like school runs and meal times. For example, if they are called away on a sudden adventure, they might have to quickly arrange for someone to look after the kids.
Another challenge is the emotional aspect. The adventurer may have to deal with the kids' fear and worry when they go off on adventures. Also, the adventurer themselves might feel guilty for not being around as much as they would like. They may worry about the impact of their adventurous lifestyle on the kids' development.
They could involve the kids in some of their adventures in a safe way. For instance, taking them on a nature hike which is an adventure but also a family activity. This way, they can keep their adventurous side alive and also bond with the kids.
One challenge could be Naruto's impulsive nature. He often rushes into things without thinking, and Tsunade would have to find a way to rein him in. Another might be dealing with Naruto's fame. Since he is the Jinchuriki of the Nine - Tails, he has a lot of attention on him, and Tsunade would need to protect him from those who might want to use or harm him.
One challenge could be the public perception. The wizarding world may not be very accepting of Hermione raising Voldemort's daughter. There could be a lot of fear and suspicion. Another challenge is Delphini's own nature. Since she has Voldemort's blood, she might have some inborn dark tendencies that Hermione has to constantly fight against. Also, Hermione would have to deal with the memories and legacy of Voldemort that might be a part of Delphini's upbringing.
One challenge Naruto might face is Gaara's past traumas. Gaara has been through a lot of pain and isolation, which has made him distrustful. It would be difficult for Naruto to break through those barriers and get Gaara to open up. Another challenge could be the political situation. Suna and Konoha have had their differences in the past, and some in Suna might not be happy with Naruto's influence on Gaara. Naruto would have to deal with any potential political unrest or opposition from those who don't trust Konoha.
One challenge would be Harry's strong will. He has his own beliefs and values that are opposed to Bellatrix's dark ideology. Another challenge could be hiding Harry from Voldemort. Voldemort might not approve of Bellatrix raising Harry in her own way. Also, Bellatrix herself has a reputation to uphold among the Death Eaters, and raising Harry could be seen as a risky and strange move.
One challenge could be dealing with their different personalities. Each sibling might have their own desires and goals. For instance, one might be more interested in military matters while another in the arts. Rhaenyra would have to find a way to nurture all of them individually.
In the fanfiction, Kakashi might face the challenge of Naruto's insecurities. Naruto has always had a complex about being alone and not having a family. Kakashi would have to find ways to make Naruto feel secure and loved. Also, dealing with Naruto's powerful and sometimes uncontrollable chakra could be a problem. Kakashi would need to train Naruto to master his chakra properly without it overwhelming him.
One challenge May could face while growing up is peer pressure. For example, if her classmates were into certain trends like wearing expensive clothes or using the latest gadgets, she might feel left out if she couldn't afford them. Another challenge could be academic stress. If she had difficult subjects like math or science, she might struggle to keep up with the coursework.
One major challenge would be understanding the magical world. Tony Stark is a man of science, and magic operates on very different principles. He'd have to learn about spells, potions, and magical creatures. Another challenge could be dealing with the wizarding community. They have their own traditions and laws, and Stark might find it difficult to fit in or make sure Harry follows all the rules. Also, protecting Harry from magical threats might be tough for Stark as his technology might not always work against magic.
Financial difficulties could also be a problem. Naruto might not be well - off initially, and raising a child requires money for things like food, clothes, and education. He would have to find ways to provide for his sister while still being a ninja. Also, there could be threats from Naruto's enemies who might try to target his sister to get to him.