Emi and Thomson's Relationship

This post is just for an opportunity to let people understand why Emi and Thomson were so quick to fall in love and to get to the point in Part 12. Many things will become apparent when I start their individual background stories.

Firstly, Emi.

Emi is perhaps a character who many of you will have thought to be simple to understand. A nervous, inexperienced Quarian girl who finds herself in a bad situation when the Reapers hit Earth. But I believe, after a thorough analysis, she is rather complex.
When you, the reader, first met Emi, she was on Earth. Thomson and Renswick were trying to escape from the Husks and they kind of ran into each other.
Emi had seen no other survivors at this point. She had seen no Husks. She saw two Alliance soldiers who wished to help her to escape and thought herself lucky. Her fear and sadness were probably the contributions to this as she would not normally trust strangers, but saw no other option.
Quarians are treated badly in terms of inter-galactic relations. I hinted at this several times in the story. The reason for this is that they created the Geth, who usually aren't very nice. And several have been known to steal.
As you may have been able to see, I did not agree with how the Quarians were treated in the Mass Effect games. I witnessed myself, a Quarian slave on sale on the planet Illium (who I managed to free). I feel sorry for their race. They should not be held responsible for something that happened a long time ago.
Because of the way they are treated, Emi will have been glad to see someone who treats her with respect and is kind to her. In turn, she found herself opening up to Thomson and telling him about the Quarian way of life.
Thomson bought her a collection of books on the Citadel whilst she was in hospital. In her individual story you will see how much the single book she had already owned influenced her judgement when it came to love.
The amount of times Thomson had rescued her made her trust him. She trusted him as soon as he had rescued her from Earth. She would start feeling safe around him and comfortable when he was with her, which would eventually lead to the first stages of their relationship.
I don't know if any of you noticed (please say so in the comment section if you did), but she told Thomson who the Cerberus operatives were even though they threatened to torture her if she told anyone. This was intentional. She would have felt absolutely terrible and thought that being tortured would have been better than betraying the one she loves.
When it came to the video message that Cerberus made her send to Thomson, she only will have done so because they'd have killed them both if not. And I also hinted at the fact they hurt her which would have probably made her anyway.
Emi clearly loves Thomson a lot. She worries about him and wants him to be safe. But as a Quarian she would feel inadequate for a human. In Part 11 she asked, and unless you want a better word for it... She asked if Thomson still wanted to have sex with her. Her feeling of inadequacy is also given a mention during the most when she realises she is in love. She compares herself to a human woman who walks past her - and points out that her suit is a physical and mental barrier between her and Thomson's relationship.
With any race of alien or human who wouldn't wear a suit like the Quarians have to, they can be seen and touched much easier than Thomson could see and touch her. She hints at her suit being a prison, even though it is the thing that keeps her from dying.
The main point of the relationship between the two characters that I wanted to get across is that she is not a human. She is a Quarian. And Quarians are not used to relationships, even among their own species. Many die whilst still being a virgin because being capable of anything of the sort is incredibly hard for them with the risk of disease. A character from the actual Mass Effect games says "the most intimate thing we (they) can do is link suit environments".
Even though in Part 12 everything was done as carefully as possible, Emi still could have gotten ill. That's why anything of that sort with Quarians is the ultimate sign of love and trust.
Emi in general is an outcast amongst the Quarians. As I said in the story, their race are extremely good with technology. But Emi is not. She preferred reading over studying technology and this left her slightly useless, hence why she was sent as an ambassador. The Migrant Fleet had no other use for her.

Now for Thomson. He is the average special operations soldier. Shoots to kill, has had enough training to suit pretty much any eventuality and is a rather fast thinker. He travels in an outdated space craft which he has become attached to, despite being regarded as useless.
When he and Emi met, he felt protective over her and made excuses to Renswick even though he didn't actually need to take her with him. His protection over her doubled with the incident with the undercover Cerberus operatives. He nearly killed them.
Alike to Emi, he is also inexperienced in relationships. He has spent his entire life in the military so didn't have the time to fall in love with anyone.
I'm pretty sure he'd do anything for Emi. He launched a nearly suicidal mission to save her and also volunteered for the operation to become the Human-Reaper so she would be safe. He cares for her and respects her. And he views her being a Quarian as a positive rather than a negative.
As for the reason why he actually loves her, I think it is partly because of the fact she is a good influence on him. She dislikes violence and he is trained to kill people. She's light to his darkness. He considers Emi an incredibly nice person and trusts her with his life.
Thomson's love is a lot easier to explain than Emi's.
Note: in the end Thomson did translate keelah se'lai wrong. This was an intentional event in the story. Keelah se'lai actually translates as 'by the home world I hope to see one day' - referring to the Quarian planet of Rannoch that the Geth invaded. Anything to do with the home world whether with that phrase or simply 'keelah' ('by the home world') are some of the more meaningful phrases in the Quarian language.

So yeah. That's the post that might help you to understand the pair.