Guru is energy thru which the jnana or knowledge flows to the shishya or disciple. If you take shishya to be ice cold stone and the jnana to be hot boiling water; then the Guru pours this hot water on the ice-cold stone, gradually drop by drop; lest the stone cracks with thermal shock. Guru takes full responsibility of shishya and monitors him every second. Guru literally carries the shishya, on the journey of evolution. He is not someone who does sweet talk or makes empty promises. Guru needs nothing from us; it is we who need him. He is a mirror who shows us what we actually are and also helps us to elevate ourselves, provided we want to rise.
Guru’s first sign is ‘Vairagya’ or detachment. As soon as one comes near the Guru, he experiences the same Vairagya – within. The guru possesses enormous energy, radiance and attraction associated with Yoga. A shishya experiences the glow and attraction in Guru’s company and feels good. Guru has noble character & pious. He has control over senses & is ever engaged in Japa, and devoted to the worship of his Ishta Devta.
Once you call somebody your Guru, you must walk the path shown by him with full faith & devotion. Anything less, any doubt, or change of path, amounts to disrespect for Guru. The journey which begins when you meet your Guru, requires continuous and dedicated practice which when followed as niyama culminates into Yoga.