Shyla Starhearth is the High Priestess of Tavril and the voice of the gods. She is the one that keeps the Guardians in faith. It is her compassionate nature, kind words of wisdom, and sage advice that help the Guardians stay whole and dedicated to the Vigil. She is a stunningly beautiful High Elf, Ascended along with many others on Thedeor Field when the Mathosian armies fell to Aedraxis's evil power.
The love Shyla had for the elven prince Hylas is legendary, as is their heart-breaking division after Aedraxis came to power. For over a century they were together. They loved so deeply that the songs sung about them could fill the library at the Chancel of Labors. They had no secrets, no arguments, no doubts. Their love was perfect. Until Aedraxis the tyrant became king.
When Mathosia called on the High Elves for aid in the battle against Aedraxis and his endless court, the leaders of the High Elves were of split mind. Shyla, ever concerned for the other beings of Telara, wished to lend aid to the Mathosians, sensing that if Aedraxis was not stopped, all of Telara would be in danger. Prince Hylas, on the other hand, urged that the Elves stay out of it. He did not want to risk losing Elven lives when they had not recovered from the Kelari Exodus. He believed that the civil war in Mathosia was a personal matter and didn't in any way effect the Elves of the wood and that they should ignore the plea for aid.
Their argument, though fierce, was something of a political argument. It did not break them apart, for their love was eternal. But they could not agree on this matter. Despite his urgings, Shyla decided to lead the Elven people to Thedeor Field to fight alongside the Mathosians against the evil of Aedraxis. Unfortunately, all on that field were slain, including the Priestess.
After her glorious resurrection as an Ascended, Shyla ran straight home to Hylas as soon as she could. However, she found him much changed. She explained to him that the Vigil had spoken to her, had chosen her as their champion against the evil cults and the Blood Storm attacking Telara. He was cold, bitter, jealous. He was suspicious of her new status as chosen of the gods, and resentful. He professed that there was no proof it was even the gods that had resurrected her. Saddened and confused, Shyla nevertheless stuck by him, forgiving and loving him despite his actions and trying to repair the damage done by their recent parting.
But they argued again, this time heatedly, bitterly, with cold finality. Shyla again wanted to help others other than her own people, when the leaders of the newly formed Guardians in Sanctum approached the Elven council with the intent of enfolding them into its ranks. Shyla welcomed this idea, wanting to help mold the newly founded Guardians into the Vigil's weapon and help protect Telara against the new threat from the Planes. Hylas refused again, citing loss of Elven lives as his reason. Shyla tried reasoning with him as often as she could, but he refused to consider it.
Finally, shockingly, Hylas withdrew from Elven society. Taking his royal Elven guard, the Aelfwar, he holed himself away in their ancestral castle, refusing to let any outsiders in. He sent a message to Shyla stating that he no longer wished to associate with her and that she had tainted the Elven people with her dealings.
Shyla was absolutely devastated. Heartbroken, she took the remaining elves to Sanctum to join the Guardians in protecting Telara.
Shyla suspects that the unrest and evil in the Silverwood is somehow connected to Hylas and his Aelfwar, along with all the Fire Rifts spawning in the forests. She fears having to confront her old lover but she is confident she will hold strong for her people. She is considered the Pentarch of the Vigil now, the High Priestess for all the gods. She is the visionary leader of the Guardians and provides advice, strategy and wisdom to its leadership alongside Cyril Kalmer and Borrin Gammult.
Shyla has the habit of taking tea with Cyril once a week to discuss strategy, battle plans and various problems about the Rifts. She very carefully never mentions anything to do with Hylas, and is amused by Cyril's attempts at concern and fatherly care.
Update Nov, 2016*- Shyla plays a pretty big role in the newest expansions, where she guides and protects the baby dragon Tasuil, and can be found with him in the new zones, wearing new armor. It seems she has finally taken a more active role in the defense of Telara.
References: For the most part, all info on Shyla is easy to come by if you read the quests in the tutorial Mathosia zone, as well as do complete the Saga of the Aelfwar questchain, where you learn quite a bit about her and Hylas. There's also a few artifact sets about her famous love affair with the Aelfwar prince, and their sad falling out. In Greenscale's Blight you witness her confront Hylas for the last time and you can tell she still cares about him but she knows that she can't let that interfere with her duties to the Vigil. I was actually quite shocked to see Shyla in Alittu, with the adorable dragon Tasuil, and you even get a quest where you have to escort her and the dragon out of town because no one wants them there anymore. I'm happy that NPC's are finally getting some more attention in Rift other than just to sit in Sanctum looking bored all day.