Tabbed by Isthebest!
this is actually a more revised version of Tobias Rezende
His version was pretty accurate but it was missing a few things.
for one thing: tuning is half a step down.
(Verse 1)
eb|----------------------------------------------|
bb|----------------------------------------------|
gb|---9-----------8-----------9---------9--------|X2
Db|--9-9-9-9-9---9-9-9-9-9---9-9-9-9-9-9-9-9-9-9-|
Ab|-7---7-7-7---6---6-6-6---0---0-0-0-0---0-0-0--|
Eb|----------------------------------------------|
(Chorus 1)
(figure out strumming pattern youself, it's not hard! XD)
eb|----------------------------------------------0000-0000-0000|
bb|----------------7777-7777-7777-5555-5555-5555-0000-0000-0000|
gb|-9999-9999-9999-8888-8888-8888-6666-6666-6666-2222-2222-2222|X2
Db|-9999-9999-9999-9999-9999-9999-6666-6666-6666-2222-2222-2222|
Ab|-7777-7777-7777-6666-6666-6666-4444-4444-4444-0000-0000-0000|
Eb|------------------------------------------------------------|
[ Tab from: https://www.guitartabs.cc/tabs/m/marianas_trench/beside_you_tab.html ]
(Verse 2)
eb|----------------------------------------------|
bb|----------------------------------------------|
gb|---9-----------8-----------9---------9--------|
Db|--9-9-9-9-9---9-9-9-9-9---9-9-9-9-9-9-9-9-9-9-|
Ab|-7---7-7-7---6---6-6-6---0---0-0-0-0---0-0-0--|
Eb|----------------------------------------------|
(And Then)
(think of strumming pattern yourself)
eb|-----------------------------|
bb|-----------------------------|
gb|-99999---88888---9999999999--|
Db|-99999---99999---9999999999--|
Ab|-77777---66666---0000000000--|
Eb|-----------------------------|
(Chorus 2)
(figure out strumming pattern youself, it's not hard! XD)
eb|----------------------------------------------0000-0000-0000|
bb|----------------7777-7777-7777-5555-5555-5555-0000-0000-0000|
gb|-9999-9999-9999-8888-8888-8888-6666-6666-6666-2222-2222-2222|X2
Db|-9999-9999-9999-9999-9999-9999-6666-6666-6666-2222-2222-2222|
Ab|-7777-7777-7777-6666-6666-6666-4444-4444-4444-0000-0000-0000|
Eb|------------------------------------------------------------|
(Bridge)
eb|------------------|
bb|------------------|
gb|-6-8-9-8---222222-|X2
Db|-6-8-9-8---222222-|
Ab|-4-6-7-6---000000-|
Eb|------------------|
(second time around play this after)
eb|------------|
bb|------------|
gb|-4444444444-|
Db|-4444444444-|
Ab|-2222222222-|
Eb|------------|
play verse 1 once and then play chorus 1 for the last time!
ending is muted strums.
ENJOY!