There are several legends related to the emergence of the Ardhanarishvara. This half male-half female form also finds mention in the Mahabharata epic. According to the Skanda Purana, Maa Parvati asks Lord Shiva to permit her to stay with him forever, embracing him "limb-to-limb". Ardhanarishvara was thus formed. The Matsya Purana relates that Brahma, pleased with Parvatis penance rewards her with a flawless golden complexion. This makes her many times more attractive to Shiva, who fuses into her to form the Ardhanarishvara.
In the Kalika Purana, Maa Parvati suspects Shiva of infidelity, when she sees her own reflection in Shiva. An argument ensues between them. Thereafter, Parvati wishes to stay eternally with Shiva, fusing with him as one single body.
Yet another lore about Parvati's jealousy when she sees Ganga perched on Shiva's head. Though Shiva tries to appease her by placing her on his lap, Parvati continues to be upset. This is when Shiva unites with the Goddess in the form of Ardhanarishvara.
As per Shiva Purana, Brahma once faced with a steep decline in the pace of creation. A flustered Brahma approached Shiva for help. Shiva appeared before him in the form of Ardhanarishvara and goddess then created various female powers from her body, thus speeding up the process of creation.
According to one interpretation, Goddess Parvati once playfully closed the eyes of Shiva, thus plunging the entire world into darkness. All living beings on earth suffered due to this eternal darkness. Uma, realizing her folly, was forced to leave Kailasha and started to worship the ShivaLinga in order to absolve herself of her sin and to reunite with her Lord. Lord Vishnu then gave her instructions on the austerities to attain her Lord once more. At this time, demon Mahishasura, came to the fore and started disturbing those of earth. This is when Uma takes the form of Devi Durga and engages in a long battle with him, finally slaying him. Lord Shiva then manifests as the Fire on top of the hill. He then merges into Devi Maa and gives darshan as the Ardhanarishvara, with the Devi as his left half!! ✨👁🐍🔱💀⌛️🌙🌀🌿📿🕉🌷🐚🌈🔔🎨✨