Guru Pathik was a nomadic supercentenarian who had great knowledge of the Spirit World and its effects on normal humans, as well as the nature of the Avatar and the Avatar State. He was spiritually enlightened and had helped numerous people, as well as animals like Appa, attain their full potential and cleanse themselves of pain and suffering. Pathik was willing to teach everybody who wished to learn from him, and his nationality was unclear, as he did not seem to hold an allegiance to any one nation and preferred to operate outside of borders.
Born in 50 BSC, Pathik was a spiritual brother of the Air Nomads and a personal friend of Monk Gyatso. When the Air Nomads were wiped out, Pathik then took up residence in the Eastern Air Temple. Many years prior to Aang's freeing from the iceberg, he had a vision of one day helping the Avatar.
In the Eastern Air Temple, Pathik met Appa and understood that he was not the person Appa expected. He simply lied back, looked at Appa every so often, and received a growl in return. Eventually, night settled in, and Appa fell asleep. The guru read Appa's spiritual energy, remarked on how Appa was so full of love and trust, but that at the same time fear was moving in where trust should have been. He also told Appa that he had had a vision of Aang and Appa years ago, and had decided to come to the Eastern Air Temple and wait for the two. He then left Appa to rest, and said that Appa must let the clouds in his mind part and be at peace.
Come morning, Appa followed a trail of fruit made by the guru, which eventually led Appa to the guru meditating with a group of animals surrounding him. Appa decided to leave the man alone, and, after flying around a bit, he came to rest next to the guru at the top of the temple. The guru gave Appa a note, which he tied to his horn, and then proceeded to tell Appa about how much his energy and Aang's were intertwined. As he told Appa this, he placed his hand on Appa's forehead, and told Appa where to find Aang. Appa flew off, heading to Ba Sing Se. However, the guru's note was intercepted by Long Feng, but was later returned to Aang.
Aang eventually arrived at the Eastern Air Temple and found Guru Pathik meditating atop the same pillar he was on before Appa's departure. Guru Pathik introduced himself as a spiritual brother to the monks and a close friend of Monk Gyatso. Aang asked the guru how he planned to teach him to open and control the Avatar State, to which the guru replied that he must first bring balance to himself before he can bring balance to the world. He first asked Aang to drink a strange liquid. Aang did so without any qualms before he spat it out, surprised by the disgusting onion and banana concoction.
At the Eastern Air Temple, he began Aang's instruction of the chakras, teaching the young Avatar of the nexuses of metaphysical and biophysical energy in the human body. In order to master the Avatar State, Pathik told Aang that he must first open all seven chakras of the body. After he determined that Aang had absolutely no knowledge of the nature of chakras, Pathik proceeded with a visual representation. Using a pond clogged with algae, he successfully explained to Aang the concept of chakras. He stated that by removing the clogs between pools, the water was allowed to flow, just as energy was allowed to flow through the body when the seven chakras were opened. There were in total seven chakras within the body, each with a different purpose and type of blockage; an intense sensation resulted from the opening of them all. Pathik warned that the process of opening the chakras could not be halted once it had begun - it had to be completed in order to succeed. Aang accepted this risk and they began the process.
Guru Pathik successfully guided Aang through the opening of the first six chakras. However, when Aang learned that to open the seventh and final chakra he would have to let go of his feelings of attachment for Katara, he refused. Guru Pathik attempted to convince him otherwise, but when Aang had a vision of Katara in trouble, he left the Eastern Air Temple to rescue her. Pathik's final words before Aang's departure was a warning that Aang risked locking the final chakra and that he would not be able to enter the Avatar State at all.
Pathik was a master of Yôga and meditation, and these skills allowed him to live for at least a hundred and fifty years. He had a vast knowledge of chakras, and the ability to read a person's emotions and feelings by reading their chi, as he demonstrated when he read Appa's. He could also sense the connections between people's energies and could enable them to find each other over great distances, as when he showed Appa that Aang was in Ba Sing Se; this appears to be a more powerful version of an ability Aang used while in the Foggy Swamp, in order to find Appa and Momo.
A guru is a spiritual expert. The word "pathik" means "the traveler" in Hindi and was a last name that Mahatma Gandhi personally gave to the family of Magan Kumar, a child born to his ashram in 1938. The Sanskrit version of the name is "Pathika", which has a wider range of meanings, such as "knowing the way or path"; as a noun, it can refer to a traveler or a guide.
Guru Pathik resembled a Hindu holy man due to his bare clothes, long, scruffy beard, and belief of "chakras".
Guru Pathik was the oldest living human character in the show, and yet he seemed to have no health problems. Interestingly, when Guru Pathik introduced himself as a friend of Monk Gyatso, Aang did not seem surprised that he remained alive to this day. Being 150, he is one of the few known people to have lived long enough to have possibly witnessed both wartime arrivals of Sozin's Comet.
Guru Pathik was also the second-oldest living character seen in the original series, human or creature, after the lion turtle.
"Guru" in Malay, Indonesian, Sanskrit, and many Indian languages means "teacher". The Filipino word "guro" also has the same meaning.
Guru Pathik knew the Avatar had returned when Aang emerged from the iceberg in an explosion of cosmic energy, due to being connected to all the energy in the universe.
Pathik was one of five known characters alive before and after the Hundred Year War, the others being Aang, Appa, KingBumi, and the lion turtle.
Zuko's Story, the manga prelude to the The Last Airbender, featured Pathik meeting Zuko during the latter's search for the Avatar. Zuko mistook Pathik for the Avatar and attacked him, but Iroh recognized the guru and demanded that Zuko release him. Pathik later returned and informed Zuko of a vision he had in which he saw Zuko standing together with the Avatar before the world, foreshadowing Zuko becoming friends with Aang.