Learn English – What’s a word for something half-submerged

I discount the too-obvious sycophant because it does not necessarily have the overtones of being a servant.

Sycophant = someone who praises powerful or rich people in a way that is not sincere, usually in order to get some advantage from them

Cambridge dictionary

Minion is relevant but does not give the complete feel of your description.

minion = a person who is not important and who has to do what another person of higher rank orders them to do

Cambridge Dictionary

There are several other candidates. Your choice may depend on context. Here are three:

Lackey = a servant or someone who behaves like one by obeying someone else's orders or by doing unpleasant work for them

Cambridge Dictionary

Flunkey =
a person who does unimportant work or who has few or no important responsibilities and shows too much respect toward his or her employer

Cambridge Dictionary

Hanger-on = a person who tries to be friendly and spend time with rich or important people to get some advantage

Cambridge Dictionary

hanger-on is similar to sycophant. flunkey or lackey seem best to fit your example, with lackey implying a little of the ill-informed awkward aggression (the "unpleasant work" of the definition) that you describe.

Lower down the employment scale we might have goon, but they tend to be employed specifically for their aggressive role. The usage is stronger in America than on the eastern side of the Atlantic.

Goon = man hired to terrorize or eliminate opponents

Merriam Webster

In slang, we also find

Junkyard-dog = (idiomatic, by extension, hyphenated when used attributively) An animal or person with an especially nasty and combative demeanor.

Your dictionary

I like this one because it combines the elements of canine dependency on the master with the mindless aggression of defending territory. I have heard it used as yard-dog but find no source.