Language and Power

Influential power: Influential Power – Is when the Person does not have power and they are trying to gain influence over you, an example would be an advertisement as they are trying to gain power over you to buy their product. 
A main theorist that would link to this would be Fairclough. He further claims that advertisements create the use of synthetic personalisation, which is a 'trick' to ensure that despite the fact that advertising is received en masse, readers feel that they are being addressed individually by a warm, and personable addresser, through the use if the second person pronoun 'you' in order to further establish a relationship between the reader and the writer. 
e.g - L'Oreal, 'Because you're worth it' the use of ' the second pronoun allows the reader to think in their minds that they are being addressed individually and therefore are more likely to buy it through the manipulation of the second person pronoun, as because once an individual gives in to buy this product, contextually L'Oreal will therefore earn more money to their company as people become more influenced and purchase it.

Instrumental power - 

Instrumental Power – When the Person already has power over usually due to authority or law, example would be a teacher in a classroom.

There are power structures in education, from nurseries to universities, but these are often concealed from those who are subject to them. Schools often produce codes or summaries or lists of rules, but these may have only a local or relative force, since the school itself is subject to laws that protect the interests of different groups.

In terms of CLA, parents tend to hold power over their children, as is the parents who have more knowledge (knowledge tends to be a form of power as a person may use this on another participant to make them feel subordinate/inferior) on the grammatical structure of sentences, as well as using verbs, nouns and determiners in the correct order, including interrogatives, imperatives, etc. 
However, influential power may not always work, for example. If a child had been asked to stop playing with certain toys, for their own safety in a subtle, warm voice through the use of a polite imperative, the child is likely to continue doing so. However, once this child has been told in a straightforward imperative through discipline, the child is likely to listen. 

BROWN AND LEVINSON - Face threatening act.
Positive politeness strategies are intended to avoid giving offense by highlighting friendliness. These strategies include juxtaposing criticism with compliments, establishing common ground, and using jokes, nicknames,honorifics, tag questions, special discourse markers(please), and in-group jargon and slang.