Because I wanted to destroy what's left of my heart, I give you the story of Destiel as told in quotes from Dean and Cas. First in the order I think works best, then in order of the episodes they were in.

"Let me tell you my story. Let me tell you everything." 

"Who are you?"

"What's the word, Cas?" 

"We're family."

"You're our brother, Cas, I want you to know that."

"I would give anything for you to not have to do this."

"I'd rather have you. Cursed or not." 

"We need you."

"I'm hunted. I rebelled, and I did it, all of it for you."

"I'm not leaving here without you."

"Don't ever change." 

"I need you."

"Dean and I do share a more profound bond."

"I've had more fun with you in the last 24 hours than I've had with Sam in years." 

"I gave everything for you."

"I love you."

"Cas, you just gave up an entire army for one guy."

"Nobody wants him here more than I do."

"I always come when you call."

"I'm Thelma and you're Louise and we're just gonna hold hands and sail off this cliff together?" "Yes."

"I could go with you."

"You can't stay."

"Dammit Cas, we can fix this!"

"I serve Heaven, I don't serve man. And I certainly don't serve you." 

"I dragged you out of hell. I can throw you back in."

"Stay the hell away from me. Next time I won't miss."

"Blow me, Cas."

"I thought you said that we were like family. Well, I think that too." 

"I prayed to you, Cas. Every night!"

"You're not my family, Dean. I have no family."

"Don't make me lose you too."

"Whatever you did, or didn't do, we'll work it out. Please man, I need you here." 

"It doesn't matter why."

"You were stupid for the right reasons...Sometimes that's all that matters."

"Of course it matters!"

"You are not the burnt and broken shell of a man that I believed you to be."

"You're not a machine, Dean."

"You don't think you deserve to be saved?"

"I won't hurt Dean."

"The only thing, I think, Dean and I have left, is each other."

"Last night on Earth; any plans?"

"You're gonna wear that? On a date?"

"Cas, not for nothing, but the last person who looked at me like that...I got laid."

"You are not gonna die a virgin. Not on my watch."

"Cas, get out of my ass!"

"I'll just... wait here then."

"Dean, you know I always appreciate our talks, and our time together."

"It's a gift. You keep those."

"I'm your huckleberry."

"I'll watch over you."

"Well, I'll go with you"

"CAS! CAS! NO!"

"And Dean?"

"I don't believe a word that's coming out of your mouth."

"Everyone you know, everyone you love, they could be long dead. Everyone except me."

"We're done."

"You're dead to me."

"Who are you?" 4.1

"You don't think you deserve to be saved?" 4.1

"I dragged you out of hell. I can throw you back in." 4.2

"I would give anything for you to not have to do this." 4.16

"I serve Heaven, I don't serve man. And I certainly don't serve you." 4.20

"We're done." 4.22

"I'm hunted. I rebelled, and I did it, all of it for you." 5.2

"Last night on Earth; any plans?" 5.3

"I'm Thelma and you're Louise and we're just gonna hold hands and sail off this cliff together?" "Yes." 5.3

"I've had more fun with you in the last 24 hours than I've had with Sam in years." 5.3

"You are not gonna die a virgin. Not on my watch." 5.3

"I'll just... wait here then." 5.4

"Don't ever change." 5.4

"The only thing, I think, Dean and I have left, is each other." 5.4

"Cas, not for nothing, but the last person who looked at me like that...I got laid." 5.18

"Blow me, Cas." 5.18

"I gave everything for you." 5.18

"You are not the burnt and broken shell of a man that I believed you to be." 5.21

"Dean and I do share a more profound bond." 6.3

"Cas, get out of my ass!" 6.19

"Let me tell you my story. Let me tell you everything." 6.20

"Dammit Cas, we can fix this!" 6.20

"I always come when you call." 6.21

"I don't believe a word that's coming out of your mouth." 6.21

"I thought you said that we were like family. Well, I think that too." 6.21

"You're not my family, Dean. I have no family." 6.22

"Don't make me lose you too." 6.22

"It doesn't matter why." "Of course it matters!" 7.17

"You're not a machine, Dean." 7.17

"I'd rather have you. Cursed or not." 7.23

"Well, I'll go with you" 7.23

"I'm not leaving here without you." 8.2

"I prayed to you, Cas. Every night." 8.2

"What's the word, Cas?" 8.8

"I'll watch over you." 8.8

"We're family. We need you. I need you." 8.17

"I won't hurt Dean." 8.17

"Whatever you did, or didn't do, we'll work it out. Please man, I need you here." 9.1

"Dean, you know I always appreciate our talks, and our time together." 9.3

"You can't stay." 9.3

"Nobody wants him here more than I do." 9.4

"You're gonna wear that? On a date?" 9.6

"You were stupid for the right reasons...Sometimes that's all that matters." 9.10

"Cas, you just gave up an entire army for one guy." 9.22

"Everyone you know, everyone you love, they could be long dead. Everyone except me." 10.22

"Stay the hell away from me. Next time I won't miss." 10.22

"You're our brother, Cas, I want you to know that." 11.23

"I could go with you." 11.23

"And Dean?" 11.23

"I love you." 12.12

"It's a gift. You keep those." 12.19

"CAS! CAS! NO!" 12.23

"I'm your huckleberry." 13.6

"You're dead to me." 14.18