For loop that iterates through files and iteratively appends lists storing values from the read file
Variable naming

Your variable's names do not convey their purpose and are even misleading.
E.g. fp and fp_2 suggest file pointers, but are actually strings.
Notwithstanding, for a better reference, I will use your variable names below.

You should also implement PEP8 (poseList vs. pose_list etc.).

Recurring declaration

You keep redefining the same constants fp and fp_2 in a loop:

for dir_name in dirs: 
    fp = '/home/Set/left'
    fp_2 =  '/home/Set/fc/fc2_0.npy'


Better declare them beforehand:

fp = '/home/Set/left'
fp_2 =  '/home/Set/fc/fc2_0.npy'

for dir_name in dirs:


Avoiding race conditions

By checking for existing files and folders using

if os.path.exists(fp) and os.path.exists(fp_2):


you've created yourself a race condition.
It is better to just try to open the file and handle the respective exception raised if something goes wrong.

Joining paths

Your path concatenation

fp+"/*.txt"


might work for you.
But there is os.path.join to do this safely and get a sanitized path:

os.path.join(fp, "*.txt")  # Leading "/" removed!


Just for the record: In Python 3 (which you are not using assuming from your print statement) you can use pathlib.Path to handle your paths:

fp = Path('/home/Set/left')
…
str(fp.joinpath('*.txt'))


Reading lines

Files are iterable, so you can get a file's lines more easily:

for f in files:
    with open(f) as pose:
        pl = [line.strip() for line in pose] 
        …