It is revealed that he did all of this for Klaus, and that the party is not a homecoming dance so much as a wake for Mikael. When Klaus goes to Tyler Lockwood's he shows him the other Hybrids he has created, like Tony his right-hand man and Mindy.
When Klaus talks to Katherine (posing as Elena) that if he dies, he's made sure his hybrids will kill Damon. Tony then said to the other hybrids to come with him and wait for Klaus to give the order to attack Mikael and anyone else who is with him.
Tony and the other Hybrids tried to save Klaus when Damon attacked him, but Katherine threw grenades (containing certain and/or wolfs bane) at them, incapacitating them. Tyler responds that he never had free will, the full moon commanded him before, and Klaus saved him from that.
In The New Deal, during the days following Stefan Salvatore's theft of his family, Klaus searched for him. When this proved to be a failure, he decided to convince Elena and Damon to help him find them instead.
Tyler called Bill Forbes (Caroline's father) to return to Mystic Falls, hoping he could help him fight off his sire bond to Klaus. Later, Tyler lost control, broke out and attacked Bill, almost killing him.
Bill told him that he has to turn every day to fight the sire bond. In Dangerous Liaisons, he calls Caroline, telling her he will come back when he's fixed.
In Heart of Darkness, Tyler returns to Mystic Falls after having turned more or less one hundred times in the Appalachian mountains, thus breaking his sire bond. However, he leaves Caroline's house after finding a picture that Klaus gave to her.
In Do Not Go Gentle, Tyler shows up at the dance to “sweep Caroline off her feet”. When Klaus arrives and asks to dance with Caroline, Tyler pretends to still be under the influence of the sire bond.
Until Bonnie breaks it, Caroline, Tyler and Klaus are unable to leave Mystic Falls High due to the containment spell placed there by Esther. In From a Cradle to a Grave, after Monique kills Hayley, the latter later transitions into an incomplete Hybrid.
The Sire Bond, fueled by motherly instincts, enabled Hayley to instinctively sense the location of her daughter, allowing her to find and re-group with Klaus and Elijah and then later her Sire. When a human loves a vampire, and is turned by that vampire's blood, they may experience the sire bond, due to the emotions that they have felt being amplified by their transition, and do their best to please their sire.
In My Brother's Keeper, and We'll Always Have Bourbon Street, it was revealed that Elena, as well as Charlotte were sired to Damon, as it was his blood that turned them. It is unknown whether the bond is maintained if the sired vampire “falls out of love” with their master.
The first is for the sire to tell the one bonded to them to forget about them and move on with their life, as Damon did with Charlotte. In Stand By Me, Damon has Elena turn off her emotions because she couldn't deal with her brother Jeremy's death.
Klaus' father, Mikael, set out and killed his wife's lover and his whole family, starting the feud between Vampires and Werewolves which has been perpetuated across the ages. Mikael had his wife put a curse on Klaus that made his werewolf side dormant.
Being the firstborn hybrid, she is an originator of a bloodline, just like her father, step-grandfather, uncles, and aunt. Her mother, Hayley, exhibited an innate ability to instinctively seek out her child and Sire, in order to complete her transition to a hybrid.
Klaus, upon realizing that Elena's blood was needed to complete the transformation, fed Tyler Elena's blood, and Tyler fully transitioned into a hybrid. Tyler is no longer under the influence of the Sire Bond, having broken it by turning into wolf from about 100 times.
Mindy was originally a werewolf from Portland, until she was successfully turned into a hybrid by Klaus. Tony was originally a werewolf from North Dakota, but he was then transformed into a hybrid by Klaus.
He appeared in The Killer, where's he being killed by Connor Jordan who shot his heart out. He first appeared in We'll Always Have Bourbon Street, later breaking his sire bond but was killed in O Come, All Ye Faithful.
She first appeared in We All Go a Little Sometimes Mad, breaking her sire bond but was the last hybrid killed in O Come, All Ye Faithful. It is possible that sire bonds are a hereditary trait, passed down from a vampire bloodline.
Every hybrid is very loyal even when acting out of free will they can't stop doing what Klaus says. It appears that this bond is not exclusive to Klaus and his hybrids, as Damon Salvatore commented that it existed with vampires also, but it was very rare.
Because of the sire bond, Elena's feelings and thoughts are somewhat controlled by Damon. In The Vampire Diaries Season 4, Episode 7 Elena is sire bond by Damon.
It was confirmed that if a creator or the progeny takes the cure for vampires; the sire bond between them will be broken. As long as hybrids are grateful to their master they will be sired, this could mean as long as vampires are in love with their masters they will be sired and to stop loving them, they turn of their switch.
It appears that this bond is not exclusive to specific classifications of hybrids, as André commented that it existed with vampires also, but it was very rare. Similar bonds exist in one form or another in numerous other settings and series.
Drawing on the concept that 'the power of the blood' endows physical and psychic benefits (and drawbacks) it has long been a staple of modern fantasy and specifically vampire fiction. Also, vampires and humans can share blood which in addition to certain physical effects, may also allow for a psychic connection.
This allows for a wide range of behaviors (minor subservience to utter adoration) and has been used as a method of conveying intimacy, loyalty and even punishment. Additionally, non-vampires that drink vampire blood would also develop a similar type of bond with the donor.
The magical world of The Vampire Diaries is chock-full of different types of mythology regarding all manner of supernatural beings, but it shouldn't surprise anyone to know that the mythology behind the vampire species is the most well-developed and explained facet of supernatural lore in the entire series. Whether it's odd because the show just didn't explain it enough, or if it's weird because it just defies logic, here are a few things about TVD's vampires that don't make any sense.
They don't have to do it in order to feed, and there is a much greater danger posed to them in terms of exposure or even possibly being hunted and killed by conspicuously murdering people. Heck, with compulsion and the healing powers of vampire blood, they can snack on anyone without even leaving any injury evidence behind.
When Liz Forbes develops cancer, Caroline unsurprisingly tries to use vampire solutions to human problems. Frankly, it's obvious that Caroline's pregnancy saga was written into the show in order to explain away actress Candice King's real life baby bump, but the idea that two fetuses could be magically transplanted into a dead body and survive unscathed is bizarre.
The whole concept behind the humanity switch is kind of an odd one, and it's clearly more of a plot device than a logical piece of mythology.