What house do you think he was in when he was at Hogwarts?
I think that Lockhart was in Slytherin when he was at Hogwarts. Firstly because he doesn't posses the traits favored by any of the other three founders. For example, let's start with Hufflepuff.
You might belong in Hufflepuff,We don't know about Gilderoy's loyalty - though it's likely that he doesn't have much to speak of - but just? It certainly isn't just or fair to wipe people's memories and then take credit for their achievements. Lockhart isn't 'unafraid of toil', either. Despite his fame, the only real work he's done is performing his Memory Charms. No, Lockhart prefers to let others do the work.
Where they are just and loyal,
Those patient Hufflepuffs are true
And unafraid of toil; (SS, p 118)
You might belong in Gryffindor,Lockhart is definitely not brave. He only takes credit for the heroic actions of others rather than performing any himself. And when the opportunity presents itself:
Where dwell the brave at heart,
Their daring nerve and chivalry
Set Gryffindors apart; (SS, p 118)
Harry, a true Gryffindor, can't fathom running away when someone is in need of help, particularly not if the required help is in one's area of expertise. Lockhart, on the other hand, thinks nothing of abandoning Ginny. So since Gryffindor is definitely out, let's look at Ravenclaw:
"You're the Defense Against the Dark Arts teacher!" said Harry. "You can't go now! Not with all the Dark stuff going on here!"
"Well - I must say - when I took the job -" Lockhart muttered, now piling socks on top of his robes. "nothing in the job description - didn't expect -"
"You mean you're running away
?" said Harry disbelievingly.
Or yet in wise old Ravenclaw,He doesn't belong here either.
If you've a ready mind,
Where those of wit and learning
Will always find their kind; (SS, p 118)
Coming from such a vain man, that's saying quite a lot. And we know that Lockhart's gifted with Memory Charms. After all, how else would he be able to convince many people that their accomplishments were actually his? But skill with Memory Charms alone isn't enough to warrant being put in Ravenclaw, and if Gilderoy has any other real talents, he certainly hides them well. Furthermore, Ravenclaw is for those who love learning above all else; Lockhart doesn't. (He's too occupied with himself. ) Many Ravenclaws would make excellent teachers because the truly wonderful teachers are those who wish to impart their knowledge and their love of learning onto others; Ravenclaws fit this bill. When Lockhart teaches, though, he only wishes to tell his students how wonderful he is. So by default, Lockhart lands in Slytherin, but it's more than that. I think he belongs there.
If there's one thing I pride myself on, it's my Memory Charms.
~Gilderoy Lockhart (Cos, p 298)
Or perhaps in SlytherinLockhart is somewhat cunning. Though he's doesn't exhibit subtlety - a part of cunning - he is definitely skilled in the art of deception, which is both a Slytherin quality in itself and the other half of cunning. And using any means to achieve their ends? Lockhart desires fame, and to achieve that fame, he suppresses the truth and reinvents his own story, stealing the feats of other people. He manipulates people - maybe not in the traditional sense of blackmail and threats - but he uses his charm and his looks to his advantage and spins lies to make people love him. Slytherin? For sure.
You'll make your real friends,
Those cunning folk use any means
To achieve their ends. (SS, p 118)
leahsm2 - Excellent point! I'll discuss it a little later.
At school, do you think he would be popular or a bit of a joke?
I think he would be a joke at school.
I agree. (But not right out of Hogwarts. ) For all that he has many Slytherin qualities, he does not share the pure-blood mania that most Slytherins have. Because of this, the other Slytherins wouldn't respect him; when they paid attention to him at all, it would only be to tease him. Also, I think none of the students from the other houses got over their biases against Slytherins enough to befriend him. We don't even know if he was good-looking at Hogwarts, and his looks are one of his greatest assets in forming his fanclub. So I think Lockhart was friendless when he was at Hogwarts.
Originally Posted by ms. leading
Lockhart is far from being a trustworthy person, so we can't assume that he's telling the truth. But why would he lie about something like this? Certainly not to counsel Harry. In fact, he's so vain that if this were not true, he would never want to insinuate that he was ever less than . . . well, 'perfect'.
But when I was twelve, I was just as much of a nobody as you are now. In fact, I'd say I was even more of a nobody!
~Gilderoy Lockhart to Harry (CoS, p 91)
As I said before, that's a really good point about Molly. But since Lockhart was a nobody at Hogwarts, would she really have even heard of him? I doubt they were in the same year, and even if they were, I picture Hogwarts-age Lockhart as someone virtually invisible, maybe just a nameless face. Shunned by his housemates and not exactly liked by the rest of the school, I see him sitting in the back of the classroom, supplying an answer when the professor calls on him; Lockhart wasn't even smart enough to be known as a know-it-all.
Originally Posted by leahsm2
Especially since he was probably younger than her, why would Molly have noticed a random Slytherin? We see Hogwarts from Harry's point of view, and when he's a 3rd - 6th year, we hear basically nothing about the younger students, save for the occassional name during the sorting. The older students simply don't notice the younger ones, especially those that aren't in their houses.
I think Lockhart reinvented himself after Hogwarts. He started caring more about his appearance and decided to make a name for himself so that he could forever leave behind the friendless kid he was as a student at Hogwarts. When Molly saw or heard his name later she didn't tie the famous Gilderoy Lockhart to the lonely boy she saw a few times at Hogwarts because the person attached to it neither looked nor sounded familiar.
Do you think his vanity is just over-insecurity?
Definitely. I think that when he reinvented himself after Hogwarts, he went a little overboard. He was determined to prove that he could be a somebody, but he had to prove it to himself first, so he began to tell himself that he was a much better wizard than he actually was. Sooner or later, he had completely fooled himself into thinking that he was above everyone else. And seeing his immense 'confidence' - or vanity - and hearing of his 'accomplishments' everyone else began to idolize him as well, over-inflating his ego.
Sorry for the really long post. I you can at least follow my ramblings somewhat!
Note: All HP book page numbers are from American ed. (paperback).