Vaishno Devi was initially called Trikuta. It is said that when Trikuta was 9 years old, She prayed Lord Rama the incarnation of Loron a seashore. When Sita was abducted by Ravana, Lord Rama along with Lakshmana and the Vaanar sena were in search of her. Along the journey, Lord Rama saw this girl in deep meditation chanting his name, impressed by her devotion, Rama blessed her.
Trikuta said she had already accepted Lord Rama as her husband. But Lord Rama was ekapatnivrata or he was faithful to Sita and would not marry any other woman. Hence he promised Trikuta to keep meditating in a cave, and he would marry her in the last reincarnation in Kali Yuga in the avatar of Kalki. Lord Rama then gave her the name of Vaishnavi impressed by her devotion. He also gave her a small army of Vanaras, a lion, a bow and an arrow to protect herself. From then on the mountains on which Trikuta kept meditating were called Trikuta Mountains. These mountains are in present-day Jammu in the village of Katra.
Read about the most intelligent Vanara making the non-rational wish? It is the story of Jambavan who asks Lord Rama for the fight: https://vedicgranth.net//jambavan-fights-krishna
REFERENCE IN MAHABHARATA
The first reference to the goddess is found in Mahabharata, when the Pandavas and Kauravas were preparing for the war at Kurukshetra. On Lord Krishna’s advice, Arjun is said to have meditated on the Mother Goddess seeking her blessings for the victory.
STORY OF BHAIRO NATH
Vaishno Devi was mediating in the cave, When Bhairo Nath saw her and immediately fell for Vaishno Devi and chased her. In this chase Vaishno devi felt thirsty and shot an arrow in the earth and a stream of water gushed out. Charan paduka is the place where she rested and that place has the imprints of her feet.
Later she meditated in a place called Ardhkanwari, some months later Bhairo Nath found Vaishno Devi in the cave of Ardhkanwari and went inside, then Vaishno Devi blasted open the other end of the cave. Then she took the form of MahanKali and cut the throat of BhairoNath. The place where Bhairo Nath temple exists is where the severed head of Bhairo Nath fell. In the final dying moments, Bhairo Nath asked for forgiveness and was forgiven by Vaishno Devi. Which is why even he is worshipped by people.