May be there is a difference between a tranquil who voluntarily agreed to the procedure and one who has it forced on them. On the whole the ones who seem to ask for it are relieved (if you can call it that) they no longer have to worry about becoming possessed. Generally they would seem to be those who either had very little magical skill anyway or were scared to death of their power. The thing is when the rite is performed I'd assume they would be very relaxed about it and may be this impacts on their subsequent demeanour.
Maddox was forcibly made tranquil. I would imagine this might also leave a mark on his demeanour. In Asunder it is stated that tranquil do not lack free will; they simply do not generally have the desire to embark on projects without someone pointing them in the right direction. When the Gallows went into melt down, Cullen admits that the tranquil were largely left to either be killed or fend for themselves. When Samson helps Maddox, the latter would remember their previous connection. He would acknowledge that Samson had helped him before, it was not Samson who made him tranquil and Sampson had been punished for his actions. Logic would dictate that he should now be "loyal" to Samson and in opposition to anyone who is an enemy to Samson because Samson is the only person who has bothered to help him.
I'd be interested to know what tranquil are like in Tevinter that have been altered by the Magisterium for crimes against the state.
Tranquil want to live rather than die, whilst in tranquil state (when restored they would rather die than become tranquil again). They can feel hunger and cold and recognise the need to remedy these deficiencies. They can recognise friends as people who are interested in their welfare and foes as people who either do not care or actively try to harm them. However, since tranquil have always been on the fringe of events or only involved when their tranquillity is reversed, it is difficult to really understand them. It would be interesting to have a tranquil companion but the writers probably feel that would be too much of a challenge because they haven't really thought through the lore thoroughly enough for it to be consistent.