The bond between Lord Hanuman and Ram is known for ages. Hanuman and Ram did not only share the relation of a devotee and God, but there is bond is special because they were brothers in a way.
There is an interesting story about Hanuman’s birth.
Apart from the story mentioned earlier:
There’s another interesting story of how Lord Hanuman was born from the air. Here it is:
Anajana was a common woman who served the Gods in heaven. Once someone cursed her for a minor fault of hers. The curse led her to have a monkey-like face.
In order to escape the curse, she began to worship Lord Shiva with all her sincerity. Lord Shiva was moved by her devotion and decided to bless her.
Meanwhile, in the prosperous empire of Ayodhya. King Dasharat desired a progeny. He ordered a huge sacrifice to be done. The rituals so performed emanated a divine potion. The potion was divided into three parts to be distributed among the three wives of King Dasharat, namely Kausalya, Sumitra, and Kaikeyi. The portion reserved for the youngest queen Sumitra was snatched away by a kite which flew it to a distant forest.
Queen Sumitra was given the part from the potion of other queens. Sumitra thus gave birth to two children namely Lakshman and Shatrugna, while Kausalya gave birth to Sri Rama and Kaikeyi gave birth to Bharat.
The kite who was carrying the potion happened to fly over the jungle where Anjana was meditating.
In order to end her curse, Lord Shiva directed Vayu, the god of air, to divert the potion in the hands of Anjana. While Anjana was seeking the blessings of Lord Shiva, the potion fell on her hands with the intervention of the god of air (Marut or Vayu).
Anjana took it as the divine prasad of Lord Shiva and devotedly consumed it with prayers. The potion led her to conceive and hence she gave birth to Hanuman.
Thus, in a way Maruti is also a brother of Sri Rama as he was born from the same potion from which Sri Rama and his three brothers were born.