I think this question, or the next one, were made thinking about this quadrilateral!
I'm sorry I have to answer this question today since is saturday and I have no time to do some graphic :(

Jack/Kate/Sawyer/Juliet - Lost
Well, what can I say?
The romantic rift between Jack, Sawyer and Kate began in season 1, this love triangle splitted the fandom in two from the very beginning. Throughout the first 3 series Kate is torn between these two men, they both have strong feelings for her, on one hand there is the good guy that seems the one (Jack) he'a a doctor, he's a hero he's sweet but strong... and then on the other hand there is the rugged bad boy (Sawyer) hot, mysterious, softer on the inside... Hard choice to make, expecially if you have to choose between Matthew Fox and Josh Holloway!
Then, in season 3 a new charachter appears: Juliet and the triangle become a quadrilater. She has feelings for Jack at the beginning but then she falls for Sawyer and this pairing turned out to one of my favourite of Lost!
I actually think that the relationships between Jack, Kate, Sawyer, and Juliet and its destiny had turned out to be one of the many great mysteries of Lost.
OMG in a week it'll be over!: Day 24 - A crazy love triangle/quadrilateral that worked out badly?
The Shippers Club will go on without me :'( [But I have a plan *mhuahahahah*]
I'm sorry I have to answer this question today since is saturday and I have no time to do some graphic :(
Day 23 - A CRAZY LOVE TRIANGLE/QUADRILATERAL THAT WORKED OUT GREAT?
OMG all this prettyness makes me go gaga! 
Jack/Kate/Sawyer/Juliet - Lost
We have to go back!
Well, what can I say?
The romantic rift between Jack, Sawyer and Kate began in season 1, this love triangle splitted the fandom in two from the very beginning. Throughout the first 3 series Kate is torn between these two men, they both have strong feelings for her, on one hand there is the good guy that seems the one (Jack) he'a a doctor, he's a hero he's sweet but strong... and then on the other hand there is the rugged bad boy (Sawyer) hot, mysterious, softer on the inside... Hard choice to make, expecially if you have to choose between Matthew Fox and Josh Holloway!
Then, in season 3 a new charachter appears: Juliet and the triangle become a quadrilater. She has feelings for Jack at the beginning but then she falls for Sawyer and this pairing turned out to one of my favourite of Lost!
I actually think that the relationships between Jack, Kate, Sawyer, and Juliet and its destiny had turned out to be one of the many great mysteries of Lost.
OMG in a week it'll be over!: Day 24 - A crazy love triangle/quadrilateral that worked out badly?
The Shippers Club will go on without me :'( [But I have a plan *mhuahahahah*]