When the gods rebelled against the Titans, Hekate chose to side with the Olympians. She acquitted herself so well in battle that after the gods won and the titans were bound, she was not only allowed by Zeus to remain free, but he esteemed her SO much that he allowed her to keep her portion of power in earth, realm of his brother Hades, sky, his own realm, and sea, realm of his brother Poseidon. Being allowed to infringe upon the Big Three is an unheard-of honor. It's thought that Hekate's great esteem among the Hellenes was the result of her earlier status as a tribal household goddess. She was so beloved that when she was absorbed into the ancient Hellenic pantheon, her worship spread far and wide - there is even some archaeological evidence of her in Great Britain, which, as you know, was invaded by the Romans, who appropriated a huge amount of Greek theology. According to legend, Hekate also fought in the war against the giants, and single-handedly burned the giant Klytios alive with her dual torches.
The legend in which Hekate features most prominently is the Rape of Persephone. When Hades abducted Persephone, Hekate the psychopomp and night-wanderer was the only one to hear the goddess's cry for help. When Demeter was wandering the whole earth searching for her daughter, Hekate found her and took her to the Underworld where they found her in Hades' palace. Legend seems to indicate that from that point on, or perhaps even prior, Hekate and Persephone were close friends - the Queen of Ghosts and Night Roads and the Queen of the Underworld, a sensible match. Both she and Hermes, another Psychopomp deity (and the only one Hekate is reliably said to have slept with, more a friends-with-benefits thing since she has always been a virginal (independent, unattached, self-possessed) goddess) are associated with Persephone's return to the land of the living in the spring.
Hekate is usually portrayed in maiden dress, wearing the same short tunic and hunting sandals as Artemis - in fact, she is said to hunt with Artemis for sport occasionally. She carries a pair of long torches to light the path before and behind her - she also seems to be adept at using these torches as weapons as well as her magic. She is called 'bright-coiffed', 'in saffron veil arrayed', which is probably why I see her as blond, like Athena, but with an undeniable Greek nose. She is accompanied by black dogs, one of her sacred animals (others include the serpent, owl (possibly a tie to Lilith), and polecat), and it's said that if you hear the baying of hounds on the dark of the moon, it means Hekate is prowling nearby. Sometimes it's said this means the listener is close to the gates of the Underworld, and these legends have ties to stories of the Wild Hunt and other guardians of the underworld such as the Cwn Annwn. She is the goddess of the Dark of the moon, compared to Selene and Artemis, who represent its other aspects, as the dark of the moon was considered most appropriate for witchcraft. I usually envision Hekate's dogs as large black dobermans, possibly because they have protective meaning to me, and also because I think they're gorgeous. On a personal note, when I pledged myself to Her, she was not happy with the fear of dogs I've carried since I was attacked. She sent an animal daimon in the form of a hound to basically follow me around, both as a guardian/familiar spirit and as a tool to desensitize me to that fear. It wasn't a pleasant experience in the beginning, I had some very frightening interactions with it while trying to get to know it (to this day I don't know what to call it) but it WAS successful in breaking me of my fear.
Hekate to me isn't beautiful in the soft, sensual way one usually imagines a goddess. She's the kind of woman whose power makes her beautiful, who carries herself like a queen, and while her features are nice enough, somewhat dominated by her nose, the dark intelligence in her eyes can't be denied. She speaks forthrightly, with authority but not with hubris. She knows who she is from top to bottom and no one can tell her otherwise. She is observant and watchful, an astronomer and gatherer of powerful herbs, and she knows every back-path and deer trail in the world of the living and of the dead. She isn't without the ability to laugh, and often takes dark humor from the mishaps of the Olympians, but she has a gravid seriousness about her as well as a keen and calculating eye for the movements of Fate. She acts firmly and decisively, but she can be tender and gentle when she's among friends, and thinks of Persephone as a younger sister. I often envision her with her very curly hair bound up, a few strands escaping, maybe bound with a beautiful veil or ornaments of silver and gold. Her clothing (here's some references) is the silvery-white of starlight or the deep black of the shadows, or else a dull, bone white. Ilithya reminds me of her a little, incidentally. She is fully capable of being wicked and creepy, in fact, when she's in a good mood wicked and creepy are her first stop in my experience, but playing pranks or scaring people just for the hell of it are too juvenile for her. She has a black and terrible temper, and doesn't hesitate to seek reparations in blood, but she doesn't unleash her wrath casually or for petty reasons.
Hekate has the title of triformis, or three-faced, which can be misinterpreted by some to mean that she embodies a maiden-mother-crone aspect. Some legends even say she has three heads, one of a dog and one of a serpent or goat! The truth is much more pedestrian, if you'll pardon the pun - in Ancient Greece, crossroads were generally three-way, not four-way, intersections. Hekate is the goddess of the crossroads and nothing is hidden from her sight, so later on in the ancient period, a sculptor named Alkamenes from Athens who began to portray her as actually having three-faces with his statuary, which caught on and soon dotted the landscape and dominated her shrines. Where the road leading to an individual house met the main road was also a three-way crossroads, so that's where shrines were placed. On the new moon (Hekate's Deipnon) offerings of leftovers and sweepings from the cupboard were placed in the shrine, and usually eaten by the poor. She was thought to sit at the gate and keep all evil out, and (probably due to her origins as a household goddess) she is also a midwife, one who guides the soul into life and then into the afterlife, which fits nicely with her role as shepherd of ghosts and spirits, since the Greeks did believe in reincarnation. She resides over exorcisms, purifications, and expiations.
For me personally, Hekate is a tough boss. She isn't mean, though her disregard of my comfort can seem a little cruel sometimes. She sets clear, firm goals and expects me to live up to them. When I don't, she doesn't harass me, but it's clear that I've displeased her and that I won't be allowed to progress under her mentorship until I've done my assignments. I feel she makes allowances for me as someone whose ADD makes it difficult to follow-through on drawn-out assignments - I'm generally not give time limits, but eventually I am expected to get things done. I'm not her pet project and she isn't my nursemaid - I'm a devotee (not a priestess) and it's my job to prove myself to her, not the other way around. I'm still working on finding ways to honor her regularly, daily, the way the Theoi prefer to be honored, and with libations and offerings. She expects me to pursue Arete, excellence, which is a punishing path to take, and also to pursue truth, to not shy from ugliness, and to achieve wisdom.
The triskele is her symbol. Here are some examples: