"Gordon Freeman, in the flesh- or rather, in the Hazard Suit- I took the liberty of relieving you of your weapons: most of the were government property...as for the suit, I think you've earned it.
The Border World, Xen, is in our control- for the time being- thanks to you, quite a nasty piece of work you've managed over there, I am impressed.
That's why I'm here, Mr. Freeman: I have recommended your services to my...employers. And they have authorised me to offer you a job; they agree with me that you have...limitless potential.
You've proved yourself a decisive man, so I don't expect you'll have any trouble deciding what to do. If you're interested, just step into the portal and I will take that as a 'yes'. Otherwise, well, I can offer you a battle you have no chance of winning; rather an anti-climax after what you've just survived.
"So, Corporal Sheppard, we meet at last. Please don't think that I've been avoiding you- a great many matters require my attention in these...troubled times; I do hope you understand. And now I require a further indulgence on your part: I cannot close my report until every loose end has been tied up. The biggest embarrasment has been the Black Mesa facility but I think that's finally taken care of itself.
*Explosion*
Quite so.
But there is still the lingering matter of witnesses; I admit that I have a fascination with those who adapt and survive against all odds: they rather remind me of myself. If for no other reason, I have argued to preserve you, for a time.
While I believe a civil servant like yourself understands the importance of discretion, my employers are not quite so trusting, and rather that subject you to the irrestistible human temptation of telling all, we have decided to convey you somewhere where you can do no possible harm, and where no harm can come to you. I'm sure you can imagine there are worse alternatives.
"Time, Dr. Freeman? Is it really that time again? It seems as though you only just arrived. You've done a great deal in a small time...span; you've done so well, in fact, that i've recieved some interesting offers for your services. Ordinarily, I wouldn't contemplate them, but these are extraordinary times.
Rather than offer you the illusion of free choice, I will take the liberty of choosing for you, if and when your time comes round again.
I do apologise for what must seem to you an arbitrary imposition, Dr. Freeman; I trust it will make sense in the course of...
Don't have Decay or Blue Shift, unfortunately, and as it happens, i'm now in agony due to RSI. Aiiie, the burn! So, in this case, this is where I get off.
EDIT: Oh, and to add to the HL1 entry:
If you accept the G-Man's offer:
"Wisely done, Mr. Freeman! I will see you up ahead."
Otherwise:
"Well, it looks as if we won't be working together; no regrets, Mr. Freeman. But there are a few survivors of your personal holocaust who would like to meet the man responsible for the total annihilation of their race."